Six Facets of Light

by Ann Wroe

  Thus instead of making firm declarations at the end of his Opticks of 1704, Newton left his readers with questions. ‘Are not the rays of light very small Bodies emitted from shining Substances?’ he asked. He expected a positive answer, but knew he might not get one; he hoped to clear it up one day, but could not do so yet. He would leave his ‘Hints’ ‘to be examin’d and improv’d by … such as are inquisitive’. Hooke attacked him for apparently believing that light was a material substance, but Newton had not plainly said so. Those who thought he had removed the mystery from light, reducing it to passive matter falling on the eyeball, were wrong. He had carried out his demonstrations ‘without determining what Light is, or by what kind of Force it is refracted’. The aether itself, he thought, might be light, though it was probably even swifter and more elastic; possibly the minutest rays, those ‘least Parts of Light’, never disengaged from aether, but were Nature’s ‘secret fire’. Or, in the final analysis, light might be God. There were still thinkers in the world for whom the multiplicity and velocity of light could be traced to only one source. Newton himself, his Bible thumbed to blackness and almost worn out with reading, was one.32

  Vincent van Gogh was another. In his thirties his missionary ardour convinced him that all the light he saw, and all the lights he saw, added up to God. The clear glow of a house or church at the end of a night walk; the slow ignition of street lamps as they were lit at ‘blessed twilight’, putting out yellow feelers through the mist and rain; or the ‘simple and grand’ arrival of the sun at dawn, always attended, in his experience, by larks singing. He went to the coal pits of the Borinage in 1879 because he wished to preach the way to light through darkness, symbolised for him by the pale, trusting glimmer of the lamps on the miners’ hats. In the evenings he pondered the ‘kindly’ lamplight in his own room, where the silent girl bent to grind coffee or peel potatoes and then, disappearing, left him to his Bible and the whispering gas globe that burned all night beside his bed. It reminded him that God was everywhere as light, and that all he should do was seek Him.

  For Galileo, tortured by light’s relationship to God and creation, such an answer would have been too easy. The great astronomer admitted in old age that he had never plumbed the essence of light. He would be happy, he said, to have spent all his life in prison, fed on nothing but bread and water, ‘if only I was assured that I would eventually understand it’. A lifetime of solitude and darkness, therefore – rather than a career of peering through ground-glass lenses – might give him just as good a chance of knowing what light was. A similar thought occurred to Milton, who never wrote so movingly and vividly about light as after he had lost it, and entered blindness.

  … thee I revisit safe,

  And feel thy Sovran vital Lamp; but thou

  Revisit’st not these eyes, that roul in vain

  To find thy piercing ray, and find no dawn;

  So thick a drop serene hath quenched their Orbs,

  Or dim suffusion veild.

  At Arcetri above Florence in 1638, when Galileo was under house arrest for his ‘heresy’ of insisting on a sun-centred universe, the two men met.33 Milton was still young and clear-eyed; Galileo now declared his right eye ‘lost for ever’ and his left ‘rendered null by continual weeping’. Nonetheless they talked of what he had seen through his ‘optick Glass’, Milton marvelling at the power of the old man’s vision in times past; and also, perhaps, at how much, and how little, they had grasped about light.

  Only Johann Wolfgang von Goethe, Germany’s formidable poet-scientist, claimed to have ‘known’ light.34 He did so with the same cheerful confidence with which he wore, in old age, a black coat relieved only by his chosen badge of nobility, a silver morning star. He did not consider light as something physical, despite his unstinting observations of its effects through glass, on paper and in candle flames. He recorded with reverence that it was utterly pure and untainted by colours, for all Newton seemed to say; and that it was his duty to strive for it, to the point where on his deathbed in 1832 he cried ‘Mehr Licht!’ ‘More light!’ to make the servants fling the shutters open and bathe him in it as he died. He also said, more mysteriously, that truth was ‘light rays flung out by a diamond’. Some encounter or revelation had persuaded him that this was so; he did not explain. Einstein, though, also approached the conclusion that light and truth were one. In his new world of relativity, shorn of absolutes of time or space, the only constant was the speed of light through emptiness. But what was it that travelled so, ‘to all distances without end’ in Newton’s words, curving and ‘fitting’, as necessary, striking off colours as it went?

  Near the end of his life, Einstein remarked that fifty years of conscious brooding had brought him no answer to the question, ‘What are light quanta?’ ‘Of course today every rascal thinks he knows the answer,’ he said. ‘But he is deluding himself.’ He had explained the physical phenomenon; the mystery remained.

  Yet God saw the light, that it was good, Genesis said. This seemed to be the end of the story, with no need to ask why or how. Light was good both for what it did, bringing all things to be, and in itself: beautiful, simple, instant, pure. And God divided the light from the darkness, Genesis went on.

  Darkness, though, was not so easily rebuffed. Light could not disown the black womb from which it had come. It needed it, worked with it and shone against it, as the blue sky was luminous only because it was backed by the darkness of space. Without dark, light was nothing. ‘Proud Light’, das stolze Licht, sneered the demon Mephistopheles in Goethe’s Faust:35

  Strive as it will, it cleaves, as if bound, to bodies. It streams from bodies, it gives beauty to bodies, a body stops it in its course, and so, I hope, it will perish with bodies before long.

  Light also held opposites within itself. It could be swift and still, tender and sharp, as Dante had experienced; and though it might be pure truth, as Goethe thought, it also bewitched and deceived with the shapes it made. ‘Curse the dazzling of appearances, by which our senses are subdued!’ cried Faust, lamenting that ‘Red gold, volatile as quicksilver, melts away in the hand.’ Traherne grieved over the ‘Tinsild vanities’ that had tricked him as a child, the glossy ribbons and shining farthings, and the ‘dead’ gold plate he had admired in the first noble dining room he had wandered into: always bright things, as flowers drew bees, or jewelled rings jackdaws. Any ‘glitt’ring look’, Herbert wrote, could blind a man.

  Even daylight may be a distraction. It commands the stage so busily and glaringly that nothing prevails against it. Take away light, and the unseen garden lilac suddenly drowns the world in scent; the invisible sea breathes and purrs as loudly as a great cat stretching; and human instincts are sharpened like a reptile’s, the whole skin alert to possible contacts in the dark with the unknown and the unimagined. But then light returns, doodling and dancing. Its artfulness is flame-like, and it was in this form that Ravilious most enjoyed it: fireworks, bonfires, wind-blown beams from lighthouses or cars, patches of bracken ablaze on a hillside; even the simple, friendly flare of a match.36 ‘I wish I had seen it,’ was his reaction to any outbreak he missed. ‘Have you looked up lambent yet?’ he eagerly asked his lover Diana Tuely in 1939, perhaps having described her glowing skin that way:

  here it is – of flame or light – playing on surface without burning it, with soft radiance – of eyes, sky, etc, radiant – of wit – gently brilliant. Hence lambency, lambently – Latin Lambere, to lick. There you are.

  It was good to touch, however elliptically, on the wittiness and intimacy, even cheekiness, of light.

  Trickster-light was as ubiquitous as ‘good’ light, its con-man twin and other side. Wicked spirits in the Western Isles trod out lightning from ling and bracken as they journeyed back and forth. In Irish tales the devil himself turned crottins of sheep dung into glitter-balls to deceive girls, and poisonous yellow ragwort tricked the gullible into digging for gold underground. Marsh gas bounced and drifted before travellers, luring them fro
m the safe road. Cohorts of jack-o’lanterns attacked Coleridge on his night walks, as a student, outside Cambridge. They were something of a regional speciality; Newton, growing up in Lincolnshire, would amaze and terrify the neighbours by tying to the tail of a kite a paper lantern with a candle in it, and flying it in the dark.

  In nearby Northamptonshire, ‘will o whisps’ frightened Clare whenever he saw them.37 Though crowds of them skimmed and danced round ‘our fenny flats’, especially in November and in misty weather, he could never get used to them, or feel that science and philosophy adequately explained them. He cornered one odd luminosity near Nunton bridge; ‘& when I got on the bridge I looked down it & saw the will o whisp vapour like a light in a bladder whisking along close to the water as if swimming along its surface’ – but, weirdly, going upstream. Returning home once from Ashton ‘on a courting excursion’, he met another:

  it came on steadily as if on the path way & when it got near me within a poles reach perhaps as I thought it made a sudden stop as if to listen me I then believed it was some one but it blazd out like a whisp of straw & made a crackling noise like straw burning which soon convincd me of its visit the luminous haloo that spread from it was of a mysterious terrific hue & the enlargd size & whiteness of my own hands frit me the rushes appeared to have grown up as large & tall as whalebone whips & the bushes seemd to be climbing the sky every thing was extorted out of its own figure & magnified the darkness all round seemd to form a circular black wall & I fancied that if I took a step forward I shoud fall into a bottomless gulph which seemed yawing all round me so I held fast by the stile post till it darted away when I took to my heels & got home as fast as I coud so much for will o whisps.

  The same Irrlichter, or false lights, guided Faust and Mephistopheles in their zigzag way through the obscene chaos of Walpurgisnacht, the witches’ revels. (Mephistopheles mocked the Irrlichter for trying to imitate men; one false move, he told them, and he would blow their Flackleben, their flicker-life, clean out.) Goethe put no Licht in this scene, for to him light was holy. What played across this landscape was Schein: sheen, glister, surface flash, a sham thing. It created a witch-world, not a universe for the rational or the good. Goethe had seen such lights himself when young, walking near Hanau when the coach road was washed out by rain: a succession of little lamps in what seemed to be a quarry, arranged in steps, yet moving up and down, to and fro.38 They were perhaps not lamps at all, but ‘shining creatures’. Given no chance to examine them, he could not decide whether these were false lures or blessings that danced before him in the dark.

  At the close of the Walpurgisnacht scene Ariel arrived, bringing Faust visions of wonder. Yet this being, who rode ‘on the curl’d clouds’, was still an imp and a deceiver, who would dance as fire in the rigging of ships to terrify drifting sailors. His usefulness in Shakespeare’s Tempest lay in his ubiquity: his ability to be here, there, everywhere and always, as agent, servant, enabler. (This was the very character of light described by Baruch in the Apocrypha: ‘[God] sendeth forth Light, and it goeth, and he calleth it again, and it obeyeth him with fear.’) Yet Ariel was no more biddable than the wicked Mephistopheles, who could also (‘Be here! Be there!’) pop up in a cornfield, as a black dog, in a vineyard, behind the stove. And he was no less proud than Lucifer who, though fallen, preserved his name and with it the implication that he was formed and shot through with light, Christ’s shadow twin. When Milton’s heavenly forces sent angel-spies after him, Lucifer-Satan could still fly unsuspected past them:

  A shape Starr-bright … or brighter, clad

  With what permissive glory since his fall

  Was left him, or false glitter …

  Traherne mistrusted angels ever after, once he knew that Satan too could pass himself as one.39

  The meeting of light and dark was sometimes explained, in medieval heads, as the clash between good and bad angels. The bad, created by Lucifer, became ‘all that we perceive under the form of matter’, Grosseteste wrote, while the good turned back to God. The bad were light in material shape; the good were light immaterial, of spirit, imagination or design. (Fairies, Hopkins was told by Father Byrne, an Irishman who evidently believed in them, were half-angels who had part-consented to Lucifer’s rebellion, and therefore played their tricks on men both visibly and invisibly; they might be spotted, sometimes, ‘thick as the heads of flowering grass’.) Some theologians taught that the first form of light was angels, and the Book of Enoch listed their names: Semyaza, ‘the seeing of God’, Kokabiel, ‘the star of God’, Yomiel, ‘the day of God’, and 197 others. They plotted, subverted and swore when they plunged down to earth, instructed men in weaponry, printing and the dark arts, and became the reverse of the luminous principles they were meant to be.

  Yet this dualism between light and dark was too arbitrary and too easy. Matter itself, to revert to Genesis, was shaped by divine ideas, or light. Psalm 139 made the point that the darkness hideth not from thee; but the night shineth as the day: the darkness and the light are both alike to thee. In more pagan parlance, darkness or chaos was the pre-existing nature of the First Cause, before light; and to modern physicists the universe is made much less of impulses and shapes of visible light than of hypothetical dark matter and dark energy. A single photon, passing through a double slit, seems to become two rays and then, as it constantly changes place, both light and darkness. And it was from the restless edge, clash or turmoil between these inseparable opposites that Goethe believed all colours came.

  Much debate about the nature of light – whether material or immaterial, pure or adulterated, ‘good’ or ‘bad’ – revolved round colour. Did light have colour of its own? Even if not, could colours stain it? Did it merely produce colours, or was it also composed of them? Like fallen man, fallen light no longer had the simple glow of lux about it – a glow that could be built up steadily and unanswerably with thinnest layers of gold. Its close involvement with the dark left matters in dispute.

  Transparency seemed to many the natural state of light, if purity was assumed to be its nature. That transparency might eventually become white, but only as crystal on crystal made up the whiteness of snow. Dante, standing in spirit in the sun, reported no colour there as light emerged.40 Light could mix with air, both Augustine and Grosseteste wrote, without the least corruption of its perfect nature. In Newton’s day his critic Hooke persisted in the notion that colour was a compound of light and darkness, and that the prism merely added colours to immaterial, transparent light.

  This equivalence of simplicity, purity and whiteness could barely survive what Newton discovered: all the colours of the rainbow in the differently refrangible rays of white light. It was true that sunlight, as it painted its way along his darkened chamber wall, was still ‘perfectly and totally’ white; but within it lay a whole kaleidoscope. ‘The most surprising, and wonderful composition,’ Newton wrote to a fellow scientist in 1666,

  was that of Whiteness.41 There is no one sort of Rays which alone can exhibit this. ’Tis ever compounded, and to its composition are requisite all the … primary Colours, mixed in due proportion. I have often with Admiration beheld, that all the Colours of the Prisme being made to converge … reproduced light, intirely and perfectly white.

  Palmer, at nineteen, seemed to prove this to his own satisfaction as he daringly sketched the sun: ‘Each ray the finest possible line the lines many colours, the general tone golden – the sky just above the sun dazzling white.’

  Around this time William Calvert, an engraver whose work he admired, told him definitively that light was orange. Palmer never forgot it, and said he disagreed, though the warm inherent glow of his paintings hinted otherwise – as well as the odd enthusiastic note, such as one of 1860, recording the ‘raving-mad splendour of orange twilight glow on landscape’ he had seen once at Shoreham. That same tint Jefferies saw in summer, deepening in autumn, ‘suspended in the … atmosphere, as colour is in stained but translucent glass’; he called it ‘tawny’, im
agining that it added a fleeting undertone to the long bunches of wayside grass. (‘The tawniness is indistinct, it haunts the sunshine, and is not to be fixed.’) Many writers and painters assumed light must be yellow, the hue par excellence of happiness and brightness, as well as of the principal flowers of spring, when light returned. ‘Life looks as fair at this moment,’ wrote Thoreau in February 1841, ‘as a blond dress in a saffron light.’ Jefferies believed that the yellow of buttercups, which dusted children and made their chins shine, must also stain the rays that fell through the air.

  Coleridge, typically, was less sure what he thought.42 In bed with a nervous attack in 1801, too prostrate even to say much to Wordsworth when he visited, he mused on ‘the prismatic colours transmitted from the Tumbler’ and found them changing into each other, orange to violet to ‘Peagreen’, when he closed his eyes. In this kaleidoscope, clear glass seemed lost. His observations of Nature also seemed to show light changing colour, as when he thought moonlight was modified from ‘its natural blue whiteness’ by the colour of a bottle-green sea. Hopkins seemed on principle to disagree: he was surprised, when lightning struck outside, to hear a colleague call it ‘rose-coloured and lilac’, and dismissed as ‘sillybillying’ the idea that white moonlight could be tinted, as Coleridge thought, ‘blue or bottleglass’. Yet he too spoke of ‘fond yellow hornlight’ and ‘bufflight’ as night approached, suggesting such adulteration was possible. He also discovered in 1873, in Hodder Wood near Stonyhurst, that bluebells seemed to lend their colour to light; that light, ‘beating up from so many glassy heads’, became an emanation of their blue, ‘[floating] their deeper instress in upon the mind’ until it flowed above as Mary’s veil, sanctifying the woods. This effect could not be seen with flowers he picked singly, to sketch their inscape in his journal and ‘know the beauty of our Lord’ by them. Nor was it in ‘the shock of wet heads’ he brought back to his room in bunches, long leaves already languishing and the sweet milky gum (he had tasted it) smearing his hands. It was only in unpicked multitudes that bluebells made their holy light.