Justified True Belief

(●) The physicist who discovered what light is, and had a psalm carved over the door of his laboratory. + Every time a phone finds a signal, a radio picks up a station, or a microwave heats a bowl of soup, it is running on a theory of electricity and magnetism that a Scotsman wrote down in the 1860s, now carried in the four equations that bear his name. James Clerk Maxwell took electricity, magnetism and light, which everybody had treated as three separate subjects, and showed that they are one subject. Albert Einstein, looking back from 1931, called the change in our picture of the world that Maxwell brought about the most profound physics had seen since Newton. He belongs on a Christian apologetics site for a simpler reason. In Maxwell’s own lifetime a story began to circulate that science and Christian faith are two armies at war, and that a man must pick a side. That story had a name, the conflict thesis, and its founding books appeared while Maxwell was working: John William Draper’s History of the Conflict between Religion and Science came out in 1874, and Andrew Dickson White’s A History of the Warfare of Science with Theology in Christendom followed in 1896. Meanwhile the man doing the best physics in the world was an elder of the parish kirk at Parton in Galloway. An elder is not a minister but a layman, one of the men chosen from a Scottish congregation and ordained to help govern it and to serve the bread and the cup at communion, and Maxwell took the office seriously enough to arrange his Cambridge term so that he could be home in time to officiate at the midsummer communion there. He had known his Bible from boyhood with a thoroughness his biographer called extraordinarily extensive and minute, and he prayed with sick neighbours in their cottages. One signature fact will stay with a reader. When the Cavendish Laboratory opened at Cambridge in 1874, with Maxwell as its first professor, the verse he chose to have carved over the entrance was Psalm 111:2, and he had it cut in Latin, in the wording of the Vulgate, the version Western Christians had read for something like a thousand years: Magna opera Domini exquisita in omnes voluntates ejus. The English Standard Version renders it, "Great are the works of the Lord, studied by all who delight in them." He did not think of the laboratory as a rival to the sanctuary. He thought of it as a place where the second half of that verse got done.

(●) 1831 AD: Born in Edinburgh and raised on a Galloway estate, he grew up asking of everything, what’s the go o’ that? + James Clerk Maxwell was born at 14 India Street, Edinburgh, on 13 June 1831, the only surviving child of John Clerk Maxwell, a Scottish advocate with more interest in machinery than in law, and Frances Cay. The family soon moved to Glenlair, the house his father had built on the family land in the valley of the Urr, in Galloway, and there the boy ran loose among millwrights, ponds and farm machinery. His father indulged the questions, and the standing family joke was his refusal to be satisfied with an answer: told what a thing was, he wanted to know what’s the go o’ that, and then, what’s the particular go o’ that. The happiness ended early. His mother died on 6 December 1839, at forty-seven, of an abdominal cancer. An operation had been attempted, and in 1839 there was only one way to attempt one, without anaesthetics, which nobody yet had. James was eight. What was left at Glenlair was a father and a son alone together, and the bond that grew between them in that house held until the father’s death seventeen years later. At the Edinburgh Academy, which he entered in November 1841, he arrived in home-made country clothes and a Galloway accent, and the boys gave him the nickname "Dafty," which stuck for the rest of his school years. He took no trouble to shake it off. He was fourteen when he worked out a way of drawing a family of oval curves with pins and thread, extending to more complicated curves the trick everyone already knew for the ellipse, a loop of thread run round two pins and pulled taut by a pencil. Professor James Forbes thought well enough of it to read it for him to the Royal Society of Edinburgh on 6 April 1846. At the time, as the Society’s own note records, the author had studied no mathematics beyond a few books of Euclid and the rudiments of algebra.

(●) 1850 AD: He went to Cambridge, broke down over his books, and came out of a Suffolk rectory with more than his health back. + After three years at Edinburgh University, Maxwell went up to Cambridge in October 1850, first to Peterhouse and then to Trinity, to train for the Mathematical Tripos. The Tripos was the university’s great mathematical examination, and its severity was legendary: days of papers, and at the end a published order of merit that ranked every man who sat it and then followed him about for the rest of his career. Men preparing for it read the way athletes train, under private coaches who drilled them for hours a day. In June 1853 he went to stay with the Reverend C. B. Tayler, rector of Otley in Suffolk, the uncle of a Cambridge friend. Within a few days he collapsed with what the family called a brain fever, and he was laid up for more than a month. The Taylers nursed him as they would have nursed their own son. Maxwell, whom the smallest kindness moved, said long afterwards that the experience had given him a new perception of the love of God, and one of his strongest convictions from then on, which he had from Paul’s hymn to love (1 Corinthians 13:8), was that "Love abideth, though Knowledge vanish away." His Cambridge friend, the rector’s nephew, put it more plainly: Maxwell had always attended church and taken communion in the college chapel and read widely in religion, but at Otley his religious views were greatly deepened and strengthened. He came back and sat the Tripos in January 1854. The men at the top of the order of merit were called Wranglers, and to come out Senior Wrangler, first of them all, was a title that could make a young man’s name overnight. That year it went to Edward Routh of Peterhouse, and Maxwell was Second Wrangler. Then came the Smith’s Prize, the harder examination that followed, and there the examiners could not separate the two of them: Routh and Maxwell were declared equal.

(●) 1856 AD: A professorship at Aberdeen brought him marriage and Saturn’s rings, and then the chair was abolished under him. + In 1856 the chair of natural philosophy at Marischal College, Aberdeen, fell vacant, and Maxwell applied partly because a Scottish post would please his father and leave the long summers free for Glenlair. His father died on 3 April 1856, before the appointment was announced. Maxwell was twenty-four, and went north alone. He carried north with him the Adams Prize question, set by members of St John’s College, Cambridge, in honour of the discovery of Neptune: what are Saturn’s rings made of? No telescope of the day could resolve them, which is to say that none could show them as anything but a smooth band of light, so the question could not be answered by looking at all. It had to be settled on paper. Maxwell worked at it for more than a year, and what he showed was that a solid ring would tear itself apart and a fluid ring would break into blobs. That left one possibility standing: the rings must be a swarm of separate particles, each one on its own orbit, a river of small moons. The essay took the Adams Prize for the year 1856, and he published it in 1859. More than a century later the Voyager spacecraft flew past and photographed exactly that. In February 1858 he announced his engagement to Katherine Mary Dewar, daughter of the principal of Marischal College, and they married early that June. She became his laboratory assistant as well as his wife, and that was no courtesy title: she held the apparatus and took the readings for the colour experiments and for the work on gases. A settled life seemed to have arrived. It did not stay. In 1860, Marischal College was merged with King’s College to form the University of Aberdeen, two chairs of natural philosophy became one, and Maxwell’s was the one suppressed. He applied for the Edinburgh chair his old mentor Forbes had vacated, and lost it to his school friend Peter Guthrie Tait. The greatest physicist of the century was, for a few months, out of work.

(●) 1861 AD: At King’s College London he made the first colour photograph and found out what light is. + London took him. From 1860 to 1865 Maxwell held the chair of natural philosophy at King’s College, and those five years are among the most productive any physicist has had. On 17 May 1861, lecturing at the Royal Institution on the theory of three primary colours, he did something no one had done before. The theory he was expounding held that the eye judges colour by three sorts of response rather than by sorting light into its hundreds of separate shades, so that any colour a person can see can be matched by mixing three lights in the right proportions. Maxwell decided to show it rather than describe it. He had a coloured ribbon photographed three times through three liquid filters, red, green and blue, and then projected the three plates back through those same three filters onto one screen, one on top of another. The colours of the ribbon appeared. Every colour photograph and every colour screen since, down to the phone in a coat pocket, works on that principle. In the audience, or at dinner around the same lecture, was Michael Faraday, the self-taught bookbinder’s apprentice whose experiments Maxwell was busy turning into mathematics, and who once called across a crowded lecture room, "Ho, Maxwell, cannot you get out? If any man can find his way through a crowd it should be you." In the same stretch he published the two papers that made his name for good. On Physical Lines of Force (1861 to 1862) was the one in which the speed of his hypothetical waves came out equal to the measured speed of light (T1), and A Dynamical Theory of the Electromagnetic Field (1865) set out the theory again with the mechanical scaffolding taken away, the equations left standing on their own. He knew perfectly well what he had. Writing to his cousin from Glenlair on 5 January 1865: "I have also a paper afloat, with an electromagnetic theory of light, which, till I am convinced to the contrary, I hold to be great guns." The London years were not all work. In September 1860 he caught smallpox at Glenlair, and Katherine nursed him alone in the sickroom while the servants left food at the door. He said afterwards that she had saved his life.

(●) 1865 AD: He gave up his London chair for a country house, and wrote there the book that carried his equations to the world. + In 1865 Maxwell resigned from King’s College and went home to Glenlair, at the height of his powers and with no academic post at all. It is an odd thing for a man in the middle of such a career to do, and it says a good deal about what he wanted his life to look like. He enlarged the house on his father’s plan and managed the estate. He rode out most days with Katherine. He endowed the little church at Corsock and built its manse. And at his own desk, in a valley in Galloway with nobody to answer to, he did some of the hardest thinking of his life. The retirement began badly. In September 1865, riding a strange horse, he was scratched on the head by a branch; the scratch turned to erysipelas, a spreading infection of the skin, and it brought him very low. Katherine nursed him again. Listening to her read their usual evening portion of Scripture was, for a while, the most mental effort he could manage. Out of those years came Theory of Heat (1871) and, above all, A Treatise on Electricity and Magnetism, published in two volumes in 1873. It is the book that carried the field theory to the next generation, the theory that what lies between two magnets is not empty space but a condition of the space itself, doing real work (T1). Nobody should imagine it was easy going. Maxwell wrote it as a guide to a way of thinking rather than as a textbook of results, and the men who finally made it plain, Oliver Heaviside and Heinrich Hertz among them, spent years boiling his twenty equations down to the four that now bear his name.

(●) 1871 AD: Cambridge called him back to build a laboratory from nothing, and he chose the words for its door. + In October 1870 the Duke of Devonshire, Chancellor of the University, offered to pay for a physical laboratory at Cambridge, and on 9 February 1871 the Senate created a chair of experimental physics to go with it. William Thomson, later Lord Kelvin, declined to stand. Maxwell hesitated out of what his friends called genuine diffidence, agreed to come on the understanding that he could resign after a year, and was appointed unopposed on 8 March 1871. He then spent three years doing work nobody expects of a theorist: designing a building. He went to look at Thomson’s laboratory at Glasgow and Clifton’s at Oxford, meaning to take the best of both, and he laid out the rooms by the research he intended to do in them rather than by what looked tidy on a plan. He would not order an important instrument until he was satisfied that its design was the best obtainable, which slowed everything down and was exactly the point. The Chancellor formally handed over the Cavendish Laboratory on 16 June 1874. Within a quarter of a century J. J. Thomson would find the electron in those rooms. Over the entrance, at his wish, were carved the words of Psalm 111:2 in Latin. A century later, when the laboratory moved to a new site in west Cambridge, the verse went up again over the entrance in English, put there, by the usual account, at the asking of a research student. There was one more piece of work in those Cambridge years, and it is the one that shows the man. He gave five of his last years to editing the unpublished electrical papers of Henry Cavendish, an eighteenth-century recluse who had anticipated several later discoveries and told nobody about any of them. Some of his friends thought it a waste of the best mind in Europe, and on the face of it they had a case. Maxwell thought instead that a man’s work deserved to be known, even a century late, and he repeated the old experiments himself to make sure the work was sound before he published it in 1879.

(●) 1879 AD: He died at forty-eight of the disease that had killed his mother at nearly the same age, and his one anxiety was for his wife. + The trouble began in the spring of 1877 with a choking sensation after meals. Maxwell told no one for nearly two years. He managed it himself instead, dissolving soda in a beaker at the laboratory after lunch to take the edge off the pain, and then going back to work. He finally mentioned it in April 1879, and even then only in passing, in a letter he was writing to his physician about Katherine’s health rather than his own. It was abdominal cancer. His doctor recorded the plain fact: it was the disease of which his mother had died, at the same age. On 2 October 1879, at Glenlair, he was told he had less than a month to live. He wrote to Dr Paget at Cambridge the next day, a calm account of the case with a request for help, and a stranger reading that letter would never guess what the writer had been told the day before. What the letter actually asked was that somebody be found to do for Mrs Maxwell what he had done for her while he had strength. He returned to Cambridge on 8 October, so weak he could hardly walk from the train. His parish priest, W. H. Guillemard, came nearly every day for five or six weeks. Maxwell asked for the prayers of the Church, which he knew by heart; he took special delight in sacred poetry, and one morning after an unusually bad night he recited all five stanzas of George Herbert’s "Aaron" without a mistake. He received communion four days before the end. To his old friend Lewis Campbell he said, in the last weeks, "I have been thinking how very gently I have been always dealt with. I have never had a violent shove all my life," and then: "The only desire which I can have is like David to serve my own generation by the will of God, and then fall asleep." He died on 5 November 1879, an hour after whispering to his doctor, too faint to be heard unless the ear was at his mouth, about his wife. He is buried at Parton, seven miles down the road from Glenlair, in the old kirkyard of the parish where he was an elder, beside his parents.

What He Taught

(T1) Light is a wave in the electric and magnetic field, and the field is as real as the bodies in it. + Scatter iron filings on paper and hold a magnet underneath, and the filings arrange themselves into curves. Faraday, who had no mathematics, believed those curves were showing something real: not empty space between two magnets, but a condition of the space itself, which he called a field. Most mathematical physicists of the day thought this was a picture for children, and that the real story was one body pulling on another across a gap. Maxwell took Faraday’s side and did the arithmetic. He built a mechanical model of the space between magnets, all spinning cells and rolling particles, and then asked a question anyone can understand even if the model is beyond them: how fast would a ripple travel through such a medium? A medium is simply whatever carries a wave: air carries sound, water carries the ring of ripples from a dropped stone, and the medium that nineteenth-century physicists believed filled all of space and carried light was the one they called the aether. Maxwell’s number came out of purely electrical measurements made in Germany by Wilhelm Weber and Rudolf Kohlrausch, who had never been thinking about light at all: 193,088 miles per second. The best optical measurement of the speed of light, made in France by Hippolyte Fizeau with a spinning toothed wheel, was 195,647 miles per second. Two numbers from two completely unrelated laboratories, agreeing to within about one part in seventy-five. Agreement of that kind is not the sort of thing a careful man puts down to coincidence. That is the moment at which light stopped being its own subject. Maxwell’s conclusion was cautious in its wording and enormous in its reach: light must be a wave of the same medium that carries electricity and magnetism. Nor did he stop there. If the medium could carry waves at all, then waves of other wavelengths must exist too, longer and shorter than the ones the eye happens to register, and he said so. Heinrich Hertz generated and detected them in his laboratory in 1887 and 1888, eight years after Maxwell’s death. We call them radio.

(Q) "we can scarcely avoid the inference that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena." + Source: James Clerk Maxwell, On Physical Lines of Force, Part III (Philosophical Magazine, January 1862); in W. D. Niven, ed., The Scientific Papers of James Clerk Maxwell, vol. I, p. 500. The sentence completes a paragraph comparing two numbers. Maxwell has just calculated the speed of waves in his hypothetical medium from Weber and Kohlrausch’s electrical experiments, and set it beside Fizeau’s optical measurement of the speed of light (T1). "Transverse" means the wave shakes sideways to the direction it travels, the way a rope snapped at one end does, rather than squeezing back and forth like sound in air.

(T2) Every molecule of a given kind is exactly like every other, and exact sameness in vast numbers is the mark of something made. + Pull a pebble out of a stream and no other pebble on earth quite matches it. Pull a bolt out of a box of bolts cut to the Whitworth thread, the standard size British workshops had agreed on, and any other bolt of that size will run into the same nut. The pebbles were shaped by a history; the bolts were made to a specification. The difference between the two cases, Maxwell thought, is worth stopping over, and by the 1870s the new science of spectroscopy had put molecules firmly in the second class. Spectroscopy is the reading of the coloured lines a substance gives off when it is made to glow. Heat a pinch of a substance until it burns, spread its light out with a prism, and instead of a smooth rainbow there appear bright lines at particular colours, in a pattern that belongs to that substance and to no other, as distinctive as handwriting. By the 1860s astronomers had turned the same instruments on the night sky and were finding those same patterns in the light of distant stars. Follow what that means. A molecule of hydrogen in the star Sirius vibrates in precisely the same time as a molecule of hydrogen in a Cambridge laboratory, and nobody carried it there. Maxwell’s image for this, in a lecture at Bradford in 1873, is a standards office: each molecule carries the stamp of a system of measurement as plainly as the metre bar kept in the Archives at Paris, or the double royal cubit of the temple at Karnak. From this he drew a conclusion in two steps, and it is worth watching him take them one at a time. The first step is a physical one: since the molecule cannot grow, decay, be generated or be destroyed, no process of gradual change can account for the fact that they are all alike, and nothing in nature since nature began has altered one of them. The second step is metaphysical, which is to say that it is a claim about what must be true of a thing rather than a measurement of it, and Maxwell was careful to mark the place where the physics stopped and this began: a set of things exactly alike cannot each be eternal and self-existent, and so they must have been made. He was equally careful to credit the comparison to Sir John Herschel, who had made it decades before, and to concede that science is incompetent, in his own phrase, to reason upon the creation of matter itself out of nothing. What science could say, he thought, was that it had followed matter back as far as it could go and found something already finished.

(Q) "the exact equality of each molecule to all others of the same kind gives it, as Sir John Herschel has well said, the essential character of a manufactured article, and precludes the idea of its being eternal and self-existent." + Source: James Clerk Maxwell, Molecules, a lecture to the British Association at Bradford, September 1873 (Nature, 25 September 1873); in W. D. Niven, ed., The Scientific Papers of James Clerk Maxwell, vol. II, p. 376. It is among the most quoted sentences Maxwell wrote outside his equations, and it reached the bishops fast. In November 1876 C. J. Ellicott, Bishop of Gloucester and Bristol, wrote to ask where he could find it, having already quoted the phrase "manufactured articles" in a charge he was preparing, a charge being the formal address a bishop delivers to the clergy of his diocese. Near the close of the lecture the molecules are called the foundation stones of the material universe, and the last sentence has them continuing this day as they were created, perfect in number and measure and weight (T2).

(T3) The world has points where the smallest cause decides the largest outcome, so physics does not force determinism on anyone. + Determinism is the view that the whole future is already fixed by the present state of the world plus the laws of nature, so that nothing could turn out otherwise and a free choice is an illusion. In the nineteenth century it looked as though physics had proved it. If the universe is a machine of particles obeying Newton’s laws, then a sufficiently clever calculator who knew where every particle was could read off the rest of history. Maxwell, who understood that machine better than almost anyone alive, told a Cambridge club in February 1873 why the argument does not work. The physical rule people were leaning on is that like causes produce like effects: nudge the starting conditions a little and the outcome changes a little. Aim a billiard ball a hair to the left and it ends a hair to the left of where it would have gone. That rule holds over most of the world, which is why prediction works at all, and Maxwell had no quarrel with it there. What he pointed out is that it fails at certain places, which he called singular points, where a system sits balanced so finely that an influence too small to measure decides between two enormous outcomes. The club heard a list of them: a rock loosened by frost on a mountainside, a spark in a dry forest, a word that starts a war. At a point like that, prediction is not merely difficult. It would require data that no finite being can have. Two things might be thought to follow here, and Maxwell claimed only the second of them. He did not claim that singular points prove free will, and he noted honestly that such points are isolated, so that a great deal of human conduct stays predictable in the ordinary way. What he did claim is that the confident determinism people were drawing out of physics rested on an assumption rather than on a result: the assumption that the physics of the future would simply be a magnified image of the physics of the past. The prejudice, he thought, was in the assumption, not in the evidence. It took another sixty years and the study of chaotic systems for the point to become common property.

(Q) "Every existence above a certain rank has its singular points: the higher the rank, the more of them. At these points, influences whose physical magnitude is too small to be taken account of by a finite being, may produce results of the greatest importance." + Source: James Clerk Maxwell, "Does the progress of Physical Science tend to give any advantage to the opinion of Necessity (or Determinism) over that of the Contingency of Events and the Freedom of the Will?", read 11 February 1873; printed in Lewis Campbell and William Garnett, The Life of James Clerk Maxwell (1882), ch. XIV. The paper was read to the Eranus Club, a small Cambridge society of older men that had grown out of the Apostles, the undergraduate discussion society of Maxwell’s student days. The room was not a physics audience. Among the listeners were three of the finest New Testament scholars in England: J. B. Lightfoot, F. J. A. Hort and B. F. Westcott (T3).

(T4) A scientific hypothesis must never be fastened to the text of Scripture, because the science will move and the text will be left carrying it. + In November 1876 Bishop Ellicott wrote to Maxwell with a second question. Commentators were saying that the creation of light on the first day of Genesis, before the sun on the fourth, agreed strikingly with the latest results of science. Was that a defensible thing for a bishop to say? Maxwell’s reply, written by return of post, is a small masterpiece of intellectual honesty, and it does three things in turn. It begins with a piece of detective work. He had long wanted to find out when that comforting statement first appeared in the commentaries, because the only way to know which "last result of science" a commentator had in mind is to date him, and the remark is certainly older than the wave theory of light. Then he offers the bishop a tempting modern reading: perhaps the light of the first day means not sunshine but the all-pervading aether, the invisible medium that was then believed to fill space and carry light (T1). And having made it sound attractive, he takes it away again, on the ground that this cannot be what the original author meant to convey to the people he was actually writing for. Then comes the warning, and it is the part worth carrying away. A hypothesis fastened to a text does not merely put the text at risk. It props the hypothesis up, keeping it above ground long after it should have been buried. It is one thing to give a bishop that advice and another to live by it, and Maxwell held to the same rule in his own affairs. When the Victoria Institute, a respectable society founded to reconcile science and faith, invited him to join in March 1875, he declined, and the draft of his reply survives. He thought highly of some of the society’s aims and said so plainly: men of science need to learn from Christ like anyone else, and Christians with scientific minds are bound to study science so that their view of the glory of God may be as extensive as their being is capable of. That is not the language of a reluctant member. What he would not accept was something narrower and, to him, more dangerous. The settlement any one man reaches between his science and his Christianity is his own, and it has no business receiving the stamp of a society. Such a settlement, he wrote, has significance to the man himself, and to him only for a time.

(Q) "The rate of change of scientific hypothesis is naturally much more rapid than that of Biblical interpretations, so that if an interpretation is founded on such an hypothesis, it may help to keep the hypothesis above ground long after it ought to be buried and forgotten." + Source: James Clerk Maxwell to C. J. Ellicott, Bishop of Gloucester and Bristol, November 1876; in Lewis Campbell and William Garnett, The Life of James Clerk Maxwell (1882), ch. XII. The sentence before it is the one that gives it force: "But I should be very sorry if an interpretation founded on a most conjectural scientific hypothesis were to get fastened to the text in Genesis..." Maxwell had just spent a paragraph making that very interpretation sound attractive, and then declined to recommend it (T4). The same letter takes the trouble to date the aether against the science of 1876, "which may not agree with that of 1896."

(Q) "Almighty God, who hast created man in Thine own image, and made him a living soul that he might seek after Thee and have dominion over Thy creatures, teach us to study the works of Thy hands, that we may subdue the earth to our use, and strengthen our reason for Thy service" + Source: a prayer found among Maxwell’s papers after his death; in Lewis Campbell and William Garnett, The Life of James Clerk Maxwell (1882), ch. XI. The prayer goes on, and the second half is the half that shows what he thought the first half was for: "and so to receive Thy blessed Word, that we may believe on Him whom Thou hast sent, to give us the knowledge of salvation and the remission of our sins. All which we ask in the name of the same Jesus Christ our Lord." It was not written for publication. Campbell prints it in a footnote among the ordinary details of life at Glenlair, next to the account of a visitor struck by how the master of the house led family prayers. A second fragment in the same footnote works through Psalm 8 and Hebrews 2 in the same way, moving from the moon and the stars to Jesus made a little lower than the angels.

What Christian Thinkers Made of Him

(†) He became the standing answer to the claim that a scientist must choose between his laboratory and his creed. + The timing is what makes Maxwell useful. Draper’s book of 1874 and White’s of 1896 fixed in the public mind a picture of Christianity as the permanent enemy of scientific progress, and that picture is still the background music of a great many conversations. Both books went to press within a few years of the Cavendish Laboratory opening with a psalm over its door. Historians of science dismantled the warfare picture in the twentieth century, and the work is not controversial among them now: David Lindberg and Ronald Numbers took the thesis apart case by case, John Hedley Brooke showed how tangled the real relations between science and religion have always been, and Colin Russell called the conflict thesis a historical myth. Maxwell is their best single exhibit, and the reason is that nothing about him has to be explained away. He was not a quiet believer who kept religion in a separate compartment from the working week, and he was not a man whose faith belonged to a youth he later outgrew. The deepening came at twenty-one and it held; the Bible he knew nearly by heart; he was ordained an elder in the Church of Scotland and served at his parish communion; and the last thing his physician recorded of him was a whispered concern for his wife. Christian writers today reach for him constantly, and the strongest of them reach carefully. John Lennox and Alister McGrath, both of them working scientists before they were theologians, use Maxwell not as a trump card in an argument about God but as a counterexample to a story: whatever the relation between science and Christian faith may turn out to be, it cannot be simple war, because here is a man in whom it plainly was not.

(†) His physics left Christian argument a universe that is mathematical, contingent, and not self-explaining. + Einstein, writing for Maxwell’s centenary in 1931, said that before Maxwell people thought of physical reality as material particles, and after him as continuous fields governed by equations, and that this was the most profound and the most fruitful change physics had experienced since the time of Newton. That change matters theologically as well as physically. A universe whose deepest layer is a set of equations is a universe with a rational structure that the human mind can follow, which is exactly what Christians have claimed about the world since the church fathers read Genesis and John’s prologue together. Maxwell’s own prayer asks God to "strengthen our reason for Thy service," which assumes the same thing. Two threads run from his work into later apologetics. The first is contingency, which is the philosopher’s word for a thing that exists but did not have to, the way a particular house stands on a particular hill although nothing required it to be built there. The argument from contingency says that the universe is a thing of that kind: not the sort of thing that explains itself, and arranged in a way that could perfectly well have been arranged otherwise. Maxwell put the point in terms he borrowed from the Scottish preacher Thomas Chalmers, calling it a collocation, an arrangement of things we have no difficulty imagining arranged differently. That is the ancestor of the fine-tuning discussion: the observation that the constants of physics sit in a narrow band that permits chemistry, stars and life. Maxwell got there in the Encyclopaedia Britannica article on the atom, noting that atoms with variable constants would make a world less fit for building, and then, characteristically, calling his own point a bare conjecture. The second is his insistence that science reaches a limit and knows it. In the Bradford lecture he traced matter back along a strictly scientific path to the place where science must stop, and said plainly that science is incompetent to reason upon the creation of matter itself out of nothing. Christian philosophers have made much of that modesty, because it is the opposite of the claim that physics will eventually explain everything including itself, and it came from a man who had just explained more of physics than anyone since Newton.

(†) Where he fell short: he hung an argument for God on a piece of physics his own successors overturned. + The fair criticism of Maxwell is not that he was religious. It is that on one occasion he broke his own best rule, and the break is instructive precisely because the rule was his. - The physics did not hold. The molecules argument (T2) rests on a premise stated as flatly as Maxwell ever stated anything: the molecule is incapable of growth or decay, of generation or destruction, and nothing in nature since nature began has changed one of them. Within two generations that premise was gone. Frederick Soddy identified isotopes in 1913, meaning that atoms of one and the same element come in varieties of different mass, so the perfect sameness was never quite perfect. The atom itself turned out to have parts, and to be able to lose them. And by 1957 the paper of Margaret Burbidge, Geoffrey Burbidge, William Fowler and Fred Hoyle had shown that the heavier elements are cooked inside stars out of lighter ones, which is to say that atoms do have a history after all. The uniformity Maxwell found so striking has a physical explanation, and it is one he did not have and could not have had. - It was the mistake he had warned a bishop against. Maxwell told Ellicott that a theological reading fastened to a conjectural hypothesis keeps the hypothesis above ground long after it should be buried (T4). His own inference from the identity of molecules to a Creator was fastened to the state of spectroscopy in 1873. The conclusion may well be true; a Christian has other and better reasons for holding it. The route is what failed, and it failed in the way he had predicted routes like it would fail. - A smaller fault, admitted at the time. He was, by wide agreement, not much good at teaching ordinary students. Between his knowledge and theirs he could not find a common measure, his illustrations came too fast and too strange, and at Aberdeen and London the classes suffered for it. He once told a friend who had to preach to a country congregation, "Why don’t you give it them thinner?" His biographer, who loved him, observes that the advice applied to Maxwell himself at least as often. None of this touches his character, and his contemporaries did not think it did. It touches the shape of an argument, which is the thing an apologetics reader should be watching. Maxwell’s worked example of how to hold science and faith together is worth more than the one argument of his that did not survive: the example was to keep the two honest and distinct, let each move at its own rate, and refuse to let either become hostage to the other.