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Pitch black and firelight

David Nash is a sculptor who works on a large scale, with the wood of whole trees. Lately, he has taken to setting the wood ablaze. In one work (Black Trunk, 2010) he enveloped the trunk of a redwood tree in planks and set it on fire. For a while the rising conflagration lit the sky, but when it was over the trunk remained standing. It is standing still, gaunt and black as charcoal. But its blackness does not betoken death and destruction. Quite to the contrary, it is as though the charred trunk, like a black hole, had sucked into itself all the energy of the blaze. It endures as a concentration of strength, power and vitality, ready to burst into life at any time.

Nash’s work got me thinking about how wood, the mother of all materials, is related to light, the giver of all life. I recalled that besides solid charcoal, burned pine also releases a liquid residue which coagulates as pitch. What kind of substance is this, blacker even than charcoal? And how does its blackness compare with that of a pitch-dark night? ¹

In the beginning was a pine tree. There it stood, its roots bedded in the hard ground, its upright trunk firm but thinning towards the tip, its branches and twigs swaying in the wind, all adorned with fine green needles quivering in the sunshine.

Then the navy started to build great ships, for which it needed quantities of timber. Our tree, along with countless neighbours, was felled. Brought to the sawmill, the trunk was cut into square-faced planks and beams. But for a while at least, the stump and roots remained in the ground. The ships, however, needed more than wood. They needed tar to coat the sails, ropes and rigging, in order to waterproof them and to protect them from rot. And they needed pitch to caulk the timbers, to ensure that no water could seep into the joints. For this purpose, the remaining stump was rooted up. Hacked into pieces, it was placed in a furnace and fired. The wood turned to charcoal, but at the base of the furnace, a dark brown sticky liquid ran out along a pipe, at the end of which it was collected in a bucket. This was tar. To make pitch, the tar was boiled in a cauldron, driving off the aqueous content as steam. The result was a thick, highly viscous fluid that would dry into a hard lump. But however solid it appears when dried, pitch remains fluid. It just flows very, very slowly. In colour, it is absolutely black.

In the story of the tree, what began with the white light of the sun caught in its canopy of needles ended with the blackness of pitch, drawn off from its roots and stump in their consumption by fire. Here, what happened to wood, as it was reduced to pitch, was also what happened to light, as it was extinguished. The story tells of wood and light, and its theme rests in their affinity.

To pursue this theme, let us return to the sawmill, where the trunk has been turned into beams. These days we also speak of beams of light. When the rays of the sun, low in the sky, glance through broken cloud, we say we see sunbeams. In Latin they were known as radii solis, ‘spokes of the sun’. But why should these spokes have entered the vernacular of English as ‘beams’? What do sunbeams and beams of wood have in common that would have led to the same word being applied to both? Could it have been their evident straightness? The wooden beam is a straight length of timber of thick, rectangular section, destined to carry a heavy structural load. The light beam is a ray, or a bundle of parallel rays, as of the sun or emitted from a candle. What they share, it seems, is clear-cut rectilinearity.

Yet within every beam of wood, in its grain, knots and rings, lurk the vestiges of the living tree from which it was once cut. And so, likewise, the word itself harbours traces of its past usage. In Old English, ‘beam’ simply meant any tree: not yet cut but alive and growing in the ground. Though otherwise obsolete, this usage survives in the names of common tree species such as hornbeam, whitebeam and quickbeam (also known as rowan or mountain ash). In this original sense the tree is a beam not because it is especially straight but because it rises like a column from the earth. Beaming is upward growth.

Remarkably, this is also the sense in which we first hear of beams of light. This was the light of a fire. The beam was the flame, shooting upwards into the air as the tree-trunk rises from the ground, not perfectly straight but twisting and turning in response to atmospheric conditions. It was the equivalent of the biblical columna lucis, the ‘pillar of light’ by which, in the Book of Exodus, the Israelites were guided on their way at night. The Venerable Bede, writing in the eighth century, used the word ‘beam’ in precisely this way to describe the column of light or fire ascending from the body of a saint. For Bede, as the tree-trunk grows from the earth, so light rises from the saintly body.²

Thus conceived, however, the beam of light is quite different from the ray. The ray is a line of emission, radiating from a source of energy as a spoke from the centre of a wheel. When we draw the sun, or a candle flame, it is conventional to depict rays of light as straight lines fanning out in all directions. This convention, too, gives us the familiar pointed form of the star. The beam, by contrast, is neither perfectly straight nor does it point in any direction. Rather than issuing from a source, the beam-line describes the growth or movement – literally the beaming – of the source itself. It is a line of combustion. It can flicker like a candle flame, zigzag like forked lightning, streak like a shooting star. Even sunbeams are depicted, in early medieval sources, as the twirling flames of a great fireball (Figure 2).

Ray and beam, I suggest, afford alternative ways of thinking about light: what it is, how it moves, and how it is apprehended. On the one hand, as ray, it is an energetic impulse that connects a point source to the eye of a recipient, across what could be an immense void of space; on the other hand, as beam, it is an affectation of visual awareness – an explosion that ignites as much in the eye of the beholder as in the world beholden. For in the moment of its apprehension, eye and cosmos become one. If a tree could see, its leaves would be miniature eyes, and the glimmer in each – as it strains to find its place in the sun – would be drawn down twigs and branches into a great beam. Where we onlookers would see a solid trunk, the tree would open in its vision to a world on fire. It would be a creature of the light.

Figure 2 The sun and the moon. Detail from a painting from the wooden ceiling of the stave-church of Ål, in central Norway, dating from the thirteenth century. (Courtesy of the Museum of Cultural History, University of Oslo.)

But it could be a creature of the dark as well. If there are two ways of thinking about light, then darkness, too, can also mean different things. It can mean the darkness of shade, such as when the rays of the sun, striking a solid and opaque body, cast a shadow on the ground, or when, at night, the earth shadows itself. Or it can mean the darkness that comes from putting out the fire. This is not to block the light but to extinguish it. The ‘shadow’ of the beam, if we can call it that, is the material residue that falls from the conflagration. The same tree which had once basked in the sun’s rays and cast a shadow on the ground becomes light in the flames of the fire – as beam rather than rays – and leaves its shadow in the material stuff of ash, charcoal and finally pitch. As ancient and medieval thinkers believed, pitch is born of the element of fire.³

Of the blackest of black nights, we say it is pitch-dark. But pitch darkness is one thing, the darkness of pitch another. One is defined negatively, by the absence of radiant light, the other positively, by the presence of material substance. Radiant light – the light of the sun – is said to be white. It is what we get by mixing every shade of the visible spectrum, for example by spinning a top decorated with a colour wheel. When the top is at rest we can distinguish the shades; when it spins they merge into white. These shades, corresponding to wavelengths, give us the colours of the rainbow. All the colour is in the light. No light; no colour. Black, then, is as void of colour as it is of light. The manufacture of pitch, however, tells a different tale.

Let’s return, at last, to the tree from which we began. Having cut the trunk for timber, to be sent to the mill, the roots and stump are set alight. What runs out from the light of the fire? Brown tar. What do we get when the tar is boiled to eliminate its water content? Black pitch. As Johann Wolfgang von Goethe famously argued, in his Theory of Colours of 1810, black is not the absence of colour but colour at its most concentrated.⁴ As pitch is the extract of tar, black is the extract of light: the essence that remains after the light is extinguished. Conversely, to set materials alight is to dilute their colour. So long as the fire burns – like the redwood of Nash’s Black Trunk – the flames and glowing embers give off shades of yellow and red. But once the fire is extinguished, all shades recede into black. The blackness of pitch, then, is an index not of nothingness but of infinite density, from which colours explode in the ignition of our visual awareness. All colour pours from pitch; and all colour eventually falls back into it.

Notes

1 1. An earlier version of this essay, under the title ‘Pitch’, was published in An Unfinished Compendium of Materials, edited by Rachel Harkness, University of Aberdeen: knowingfromtheinside.org, 2017, pp. 125–6.

2 2. Oxford English Dictionary, beam, n.1, III. 19a.

3 3. Spike Bucklow, The Alchemy of Paint: Art, Science and Secrets from the Middle Ages, London: Marion Boyars, 2009, p. 60.

4 4. Johann Wolfgang von Goethe, The Theory of Colours, translated by Charles Lock Eastlake, London: John Murray, 1840, p. 206, §502.