What, in the end, makes advertisements so superior to criticism? Not what the moving red neon sign says - but the fiery pool reflecting it in the asphalt.¹

Walter Benjamin, One Way Street

Happy are those ages when the starry sky is the map of all possible paths - ages whose paths are illuminated by the light of the stars.²

Georg Lukács, Theory of the Novel

Between a patch of sunlight warming the bricks in a courtyard and a fluorescent strip light revealing the pockmarked inner lining of an underpass; between the swatches of grey blotting out the sky in a storm and the droplets of rain caught in the cone of a street lamp; between the first band of pink colouring the atmosphere at dawn and the headlamps of lorries en route to their first delivery; between the red eye of sunset hovering over the river and the neon sign reflecting in a puddle - between these things there is a world of difference. It is not exactly the difference between Apollo and Dionysus, the kingdom of the sun and the kingdom of the moon, although it’s true that artificial light feels more at home in the latter. The difference rather takes the form of a grammatical-ontological function: the One versus the many, the difference between light and lights. And God said, “let there be light.” And the City said “let there be lights.”

The Impressionists taught us to see a whole new range of atmospheric effects: violet shadows in the facade of a cathedral backlit by afternoon sun, the green halo of a snow covered road at dusk. But this huge variety of colour and intensity belongs always and everywhere to the same source. Every effect, every variation, demonstrates the power of the infinite, the one true source - the sun. The miracle of artificial light, on the other hand, is the way it divides light into a thousand pieces. It has more in common with the stars than the moon. Moonlight after all is only the reflected glare of the sun, whereas stars are the distant suns of other planets. Stars give testament to a cosmos without centre composed entirely of multiplicities. An eternal, stratigraphic frieze, hardwired and a-subjective.

Looking out over a city at night, what we see is a constellation brought down to earth. And yet the stars truly are of another world. They are alterity writ large, spelt out in the dot-to-dot signature of constellations. While clouds, smog and street lamps often render them invisible, they themselves never fade, never die or rise again - at least not within the kind of timescale that human beings can fathom. The stars keep aloof from the lifecycle of the sun/moon, with its days, nights and seasons.

It seems strange then to associate artificial light with the light of the stars. Each is measured by a completely different time-scale. The life of a star is counted in aeons. It fills up time like an ocean flooding an island. The timescale of electric light on the other hand is defined by shock and flux. It is the time of the city, the factory and the cinema: tail lights at a junction, scratches on celluloid, arms jerking back and forth across a work station. But in both cases (modernity and the stars) there is a sense in which time - linear or cyclical, progressive or conservative, bourgeois or feudal - is effectively obliterated.

The aeonic time of the stars contrasts with the cyclical time of the seasons; the stellar versus the terrestrial. Cyclical or seasonal time is the lived experience of those who work the land. Habits and rituals, while they have their own unique pattern, are cut from the same temporal cloth as organic life itself. The eternal stars preside over cycles of growth, death and renewal down below.

Analogously the shock and flux of electric light contrasts with the steady linearity of liberal-bourgeois notions of progress. We find a social parallel in the fact that capitalism involves two apparently contradictory modes of social organisation: scientific planning in the individual firm versus 'free' competition in the market; totalitarianism at home, liberalism abroad. The orderly workplace nurtures an experience of fragmentation and disorder - temporal shock/flux. Meanwhile linear progress is the 'natural' outcome of chaos in the market.

In fact, shock/flux as a phenomenological experience extends far beyond the workplace. It provides the time-signature of everyday life. And linear progress means much more than the Darwinian selection of evermore rational firms. In classical liberalism it implies the evolution of civilisation as such. At the level of day-to-day business, capitalism improvises its tune on the score sheet of shock/flux. At the level of history however, it is guided by the stars. Like any good astrologist, it has faith in future fortunes but is capable of recouping disaster as a form of fatal justice, hence as a sign of rebalancing, renewal and better things to come.

In other words, capitalism splits time between two extremes. At one end it touches the stars. At the other end only fragments remain. The modern pairing of shock/flux versus linear progress, which runs parallel to to the pre-modern one of stellar versus terrestrial, gets subsumed. The opposed pairs are no longer modern versus pre-modern but temporal versus a-temporal: terrestrial cycles and linear-progress versus the eternity of the stars and the disintegration of shock/flux. Capitalism chooses the second pair, the a-temporal.

In his Philosophy of History Hegel concludes that the state must put an end to the barbarity of Cronos, who devours his own children in the endless rise and fall of civilisations. The state must become a final State, the State to end all states, the realisation of Spirit or the Absolute Idea.³ Under capitalism this idea gains a new and sometimes terrifying reality. The confident bourgeois, in his revolutionary ascendancy, truly believes that capitalism is the means to achieve this goal; while the decadent or cynical bourgeois, in his morbid, postmodern fixation, believes that we are already there. Things are less rosy than anticipated but people will learn to live with that.

This is artificial light’s secret connection with the stars: the moment that progressive disenchantment - the unmasking of superstition, myth and illusion - flips over into its enchanted other, the moment that the light of reason becomes a source of transfixiation more than illumination.

* * *

We could divide the history of artificial light into six periods: the first, accounting for the major part of humanity’s time on earth, would include log fires, candles, torches and oil lamps. The second, also a kind of fire, would cover the first half of the 19th century, the age of the gas lamp. Although gas lighting is not based on a fundamentally different principle to the kinds of lighting that came before it, it deserves a period all of its own for the sheer scale of materials and social organisation that it mobilised. If a stick wrapped in gauze, or a string embedded in wax is a kind of tool, then a gas lamp is really a component in a much wider infrastructure. One of the major problems of gas lighting, eventually solved with all the ingenuity of a Faraday or a Marconi, was how to ignite the stream of gas automatically and simultaneously across the network of lamps throughout the city. Gas light is truly a product of the industrial revolution, the first machine lighting.

The third period (roughly 1875 to 1914) inaugurates the commercial and public use of electric light in the late 19th century. Its first examples are arc lamps, where a spark leaping between two electrodes causes their combustion in the presence of air. In this sense, they are also a kind of fire - an electrical fire. And the incandescent lamps that follow them, based on carbon and then tungsten filaments, are not too dissimilar. In the glowing filament of an ordinary household bulb, it is still possible to recognise something of the primordial magnetism of fire. Although it doesn’t radiate heat like fire, and although we would never sit for hours staring into its flame, which is constant and holds no secrets, still it colours faces, objects, food and the corners of rooms with a lingering glow that offers some respite from the night. The light of burning tungsten is still the best accomplice, as good as any candle and more efficient, for warding off sleep - the oblivion of that dreamless sleep that is the sleep of labour.

Up to this point artificial light remains subordinate to the diurnal cycle of the sun. To understand the lasting power of this regime, we should recall that the first electrical street lighting consisted of arc lamps mounted on giant masts up to 50 metres tall, and were called ‘moonlight towers’. The largest ones are still standing in the US, for example in Austin, Texas, where thirty of them once lit up the city. Their industrial grandeur suits the American landscape (one imagines them side by side with oil pumps), but they also appeared in Europe. In London for example, six, twenty-five metre tall towers were installed around the Bank of England. Strange how they look like guard towers.

Engravings celebrate the spectacle of whole districts where night was abolished in a single stroke. But looking through the archives, readers from the early 21st century will probably think first of concentration camps, second of searchlights and anti-aircraft guns, third of construction yards and bomb sites like Alexanderplatz, and only fourth of the world’s fair or Luna Park.⁴ The great catastrophes of enlightenment.⁵

In the intervening years however, a whole new range of luminous substances would be discovered: vaporised sodium and mercury, the noble gases neon and argon, as well as nitrogen, carbon dioxide and helium. The names of some are as exotic as their colours, like deep sea fish or a new species of tropical orchid: electric turquoise for argon, molten red for neon. In other cases what’s surprising is the discovery of this almost miraculous property in once familiar elements. Who would have thought that carbon dioxide was characterised by its brilliant white glow? As if animals would one day exhale light.

In this fourth period light becomes something alien; alien, that is, to its maker. A thing of our own making - fully invested with human ideas and activity - takes the form of a quasi-natural phenomenon (as opposed to something ‘authentically’ natural animated by human belief). Walter Benjamin understood this when he wrote that the power of advertising lies not so much in the message spelt out by the neon sign, but in "the fiery pool reflected in the asphalt." This is the real hypnotic power of the sign, a power that exercises its force at the level of affect and sensation more than sense. The power of a neon sign subsists at the level of a blaze of autumn sun, or a summer twilight running the spectrum from turquoise to black, or any number of ‘impressionist’ effects.

The vision of this fourth period, the age of neon (roughly 1914 to 1939), swirls around us, brilliant and kaleidoscopic, like a million glowing embers dancing in the dark or shards of coloured glass falling from the sky. Futurism, with its dots and dashes of pure colour, and Cubism, which begins its decomposition of perspective by detaching facets from bodies and concludes it by discovering the text-fragment, ideogram and pattern swatch, both seem to prefigure neon by about a decade. Light becomes a sign, and the sign is defined according to its affective dimension, by shock and fragmentation.

* * *

What follows is more pragmatic. With fluorescent tubes and high pressure sodium lamps tone and line regain their hegemony over colour. If classical aesthetics privileged drawing and sculpture, then the modern impulse has famously involved a discovery of the autonomous power of colour, liberating it from outline and shading. This ‘colourism’ typically locates its origins in the painterly style of Venetians like Titian and Veronese. It comes into its own with Impressionism and becomes ecstatic with the Fauves a few years later. But during the course of postwar urbanisation, light and colour undergo a spectrum shift. See how in an office at night edges are sharpened to the point that line overtakes volume. Under fluorescent light objects near and far appear stacked up against each other, like a photograph shot in strong light with maximum depth of field. Or how on the dimmest backstreets, undisturbed by either neon signs or the cheerful glow of tungsten - streets without revelry or domesticity - it is quite impossible to tell what colour the parked cars are. Under the dirty yellow of a sodium lamp, bright enamel skins of green, blue and red, are converted into a twentieth century grisaille. The subject memorialised: naturally, the car.

The age of neon follows the same course as the early twentieth century avant-gardes. The avant-garde vision of modernity, poised between utopia and catastrophe, socialism and barbarism, is replaced in the postwar period by modernism as the universal pattern book of corporate capitalism. Hence artificial light succumbs to a kind of technological conservatism. In this fifth period, the primary factor is efficiency above all else, gauged, in the first place, by a simple metric of Watts versus Lumens. The new lights look drab compared to their polychromatic predecessors. More than this, they seem to actually drain colour from their surroundings. Early manufacturers boasted of the ‘shadowless’ light emitted by the new fluorescent tubes. The optical effects prized by the impressionists were chased out of the world along with its shadows. Where the moonlight towers had failed, fluorescent lights finally succeeded. Colour is rendered simultaneously factual and idealistic - like a chip on a paint chart. The effect is due not only to the colour temperature of fluorescent light, but also has to do with the way it spreads itself lengthways, producing a very diffuse illumination. This form - a one to two metre long strip - was vaunted for its modularity: here was the ideal light for suspending above a workbench, countertop or shelving unit. No longer the dockyard or steel mill set ablaze by arc lamps, but rather the assembly line or cubicled office neatly illuminated by fluorescents.

Is it surprising to think that this is also the age of tie-dye and dayglo?⁶ Material culture in this period takes the form of a mirror or a crystal. These traces of hippiedom and counterculture are then arrayed on the verso of a plane whose face side presents the image of row upon row of desks and honeycombed cubicles, or endless highways curling into the distance. The acid rainbows of tie-dye and the super-luminescence of day-glo are clearly a rebellion against the numbness and pallor of this strip-lighted image of the future.

Modernity has always been a two-headed beast. Every artefact of culture is a document of barbarity at the same time that it sings a note of hope - if struck correctly. And this is especially true for modernity, poised, during its mature period, between socialism and fascism. But at each turn of the historical spiral, with each new shift in our periodisation, the character of the two heads changes. The disturbing features of one head (turning from a frown to a scowl, or from a smile to a grin), elicit a change in the other. The displacement is double. In the phenomenology of the imagination traced here, we move from the grandeur and terror of capitalism - its risk, its heroism - to the stability of Fordism as a social pact involving trade-unions and the welfare state in the postwar period. The flipside of this regime will therefore tend to take the form of a counterculture - a minoritarian culture, if not a culture of the minority.

The picture is complicated because both fluorescent strip lights and high pressure sodium lamps belong to spaces which we might already call postmodern: the office, the airport, the shopping mall and the motorway (as opposed to the boulevard, rond-point or grid city). These spaces already demonstrate the indeterminacy of the non-place and the confusion of postmodern hyperspace. In other words the territory marked out by these milestones in the history of artificial light seems to extend beyond the threshold of 1973 as much as it stretches back to 1945. The ultimate basis of these overlapping time frames is the unevenness of capitalism itself. It took 30 years of upheaval - from the first motor-controlled assembly line in 1913, through wartime nationalisation and rationalisation - before society settled into a form that could properly accommodate Fordism. Or rather a form that could fully realise the vision of Fordism at the level of social totality, which is what Fordism itself, from the beginning, demanded.

Hence it was postwar Keynesian measures - meted out by the state with Fordist production at their base - that built the vast network of highways lacing their way across America’s suburbs and inner cities: the dim orange maps of the future that we know from airplane windows. Fordism would also fuel the growth of the administrative spaces that we associate with fluorescent lighting. The scale and rigidity of capital investment during this period demanded new resources in planning as well as insurance. On the other hand, the growth of capitalism’s administrative apparatus would explode in a much more dramatic way only during neoliberalism, driven by both financialisation and the spread of service industries.

The uneven speed of capitalist development leaves in its wake a variety of textures: here layers that are highly compacted, there passages only loosely woven like scrim. All of them are folded into our image of material culture, which becomes alternately creased, crystalline and porous.

The image has three levels or phases: 1, the technical-ideological driver at the heart of the image; 2, the contingent historical moment that dates the invention of the image (numerals chiseled on the milestone); and 3, surrounding this telluric material like a hologram, the image of the future. The overlap of these three produces what Benjamin called a dialectical image. In this way neon is a product of the 19th century revolution in the chemicals industry - the same that produced synthetic dyestuffs, TNT and artificial fertilisers. Its use in advertising dates from 1910, when a canny Parisian advertiser convinced chemist Georges Claude that his invention would be better suited to signage than domestic lighting. But while the street corners of 1920s Paris and Berlin would soon glow pink and green, it was only in the 1950s that Las Vegas would do away with architectonic values altogether, replacing them with an architecture of floating signs. In a parallel fashion, it was Fordist production that made fluorescent lighting the dominant form of artificial light by the early 1970s, but these lights would only become truly generic with the rise of a postmodern, supposedly 'postindustrial' capitalism 30 to 40 years later.

Today, fluorescent tubes account for about 80% of all electrical lighting. But the last two decades have brought in train a new image of the future: the white lights, xenon and LEDs (light emitting diodes). The previous generation of lamps drained the world of colour, reducing light to the mere absence of darkness; the new ones seem to impart an extra dimension to visible reality. The origin of xenon lies in cinema, while LEDs developed out of new research in electronics. The first xenon bulbs were used in cinema projectors, the first LEDs in IBM punch card readers. Together they are the lighting equivalent of HD cameras. If HD fulfils cinema’s first intentions - capturing reality more completely than the human eye, rendering it malleable, decomposable, manipulable - then xenon and LEDs do the same for electrical lighting.

Both are prized for their close approximation to daylight, and it’s true they render colours better than fluorescents or sodium (or tungsten or arc lamps for that matter). And yet there is something deeply otherworldly about these lights. Watch as an unsuspecting pedestrian passes through the beam of a xenon headlamp (fitted, inevitably, to a BMW or a Mercedes): creases in skin and fabric are etched in microscopic detail, as if submerged in a bath of caustic soda. Or see how the green pigment of a leaf dangling next to an LED street lamp is charged up like a radioactive specimen. Living things share a strange fate under this light. Rather than the corpse-like pallor associated with fluorescent strip lights, they appear X-rayed, blasted, irradiated. These are not corpses - with their bloated grey skins - but ligaments, smooth and pearlescent, muscles, dense and layered, and nerve fibres, stretched out into spiders’ webs. A living body, albeit scanned and frozen. Under the light of xenon and LEDs, we glimpse the deep tissue of the world.

Xenon bulbs (actually a kind of arc lamp) were invented in the 1940s. The first LEDs date from the early 1960s. The reason for situating them in the 21st century is their recent appearance in public space. Of course a cinema is also a kind of public space, but in an auditorium the white light of xenon appears filtered through the veil of an image. Out on the streets, it is the world itself that is transformed into an image. Meanwhile LEDs have grown steadily in power, efficiency and diversity of colour, to the point where they are no longer limited to standby buttons and calculator screens. Combined in batteries of tens or hundreds, they act like spotlights, chalking out white circles on the pavement.

LEDs are the more mysterious of the two. With this new type of light one finally leaves behind the primitive forms of combustion and ignition. With neon, mercury, sodium etc., even if the method was electrical rather than thermodynamic, and even if the gases involved were not in fact volatile but inert, one was still dealing with, at bottom, a principal of ignition - of gas exposed to a spark. To an extent fluorescent strip lights anticipated the move to solid state lighting. In a fluorescent tube, it is not the gas which produces light but rather the coating of light-emitting phosphors on the inside of the glass. They are therefore a kind of hybrid. With LEDs, the strange tendency of technology to become more and more opaque, more and more mysterious, more and more abstract or ideal - immaterial even - is finally clarified. Strange because we expect technology to render the material world comprehensible and therefore exploitable: to shine a light in the darkness. It is as if our delving into the heart of matter had uncovered, in the deepest layers, a world of impossible figures and arcane symbols.

Scientific knowledge seems to become more and more abstract, and in fact counterintuitive. Quantum mechanics is perhaps the ultimate example, a field popularised in countless films and articles, sold to a mass audience on the basis of its apparent illogicality. In the realm of ‘applied’ science we have the impression that human understanding is one step behind its own technical products, these products being constantly ejected in front of it, like a growing heap of litter pushed along by the road sweep’s broom called ‘progress’. But the unfathomable complexity of technology depends on an equally complex and unfathomable division of labour; a form of social organisation in which people are separated from the products of their labour as well as from each other’s experience. This division of labour includes knowledge production.

Marx compared the spirit of revolt to a mole, disappearing underground for years at a time before emerging in unexpected outbursts. But capitalism, too, follows the habits of the mole: it tunnels blindly. Hence its subjects are reduced to a subterranean existence. Before the great leap in the dark we shut our eyes, so that bringing the darkness inside of us, we might see more clearly the interior light of rationality itself.

Do we accept the kind of technological determinism that divides history into ages named after the latest piece of equipment? The age of the steam engine and the railway, the age of the internal combustion engine and the car, the age of nuclear power and the computer. In any case we can see how, following Marx, these innovations act like centrifuges, throwing established techniques and structures into disarray, causing some to crack in two, others to shatter in a thousand pieces, still others to shift position or recombine. LEDs are a spin-off of all the research hours put into electronics, computer science and above all, semiconductors. In fact they should be classed in the same technological genus as lasers. Like a laser, the light of an LED emerges from a single point, from a little fragment of crystal or a flattened chip of silicon, rather than a heated filament or a cloud of gas.

The small size and low energy usage of LEDs allow them to be combined en-masse to form screens. At this point we should probably include plasma screens and LCDs in our catalogue, even if their main purpose is information display rather than lighting as such.

Light is more and more subordinate to information. The greatest examples of this principle are not even visible: the transatlantic fibre optic cables responsible for millions of financial transactions every day. But in the blue glow of a smartphone we read the same message: light as information. It’s curious how this final instrumentalisation seems to correspond to a belated and unexpected re-enchantment of artificial light. The power of a screen is not the light that it casts on the world, but rather its capacity to absorb us. Our gaze no longer meets the horizon in a gesture of conquest or inquiry, but rather turns inwards. Peering into the screen, it is the viewer himself who is illuminated.

* * *

There could be few clearer examples of the dialectic that turns enlightenment into a form of blindness. The image of human beings captivated by screen-light - whether seated in formation in a cinema, or wandering alone, hooked up to their own personal device - has become a cliché of technological alienation. But what is a cliché? An image. We shouldn’t shy away from the image but instead burrow deeper below its surface. If we enter this particular image, the first thing we discover is quite simply beauty. There is something beautiful about the image of a face lit up by a screen. The image echoes across history, sending us back to the chiaroscuro of Baroque painting and the Spanish and Dutch Golden Ages: a face in the darkness, the image of human intelligence.

This is what we see in the paintings of Caravaggio, Velasquez and Rembrandt. For the first time in the Western tradition the self makes its presence felt directly in the painting. Earlier artists painted self-portraits but there was always something missing: doubt. Even in the most direct representation of the self (the self portrait) doubt was absent. The self was regarded as an object, available to direct and impartial observation. Even the mystery of Leonardo’s smiling virgins is only a halo of divinity, a mark of their unearthly origin.

What is doubtful about later paintings is not just the content (the doubt of Thomas putting his finger in Jesus’ wound, the doubt of the court painter who cannot render clearly both his own face and the back of the canvas), but rather light itself. Like the light of a screen, it is distinct and yet indiscernible. The light strikes from all angles. It is impossible to assign a single logical source. This comparison runs counter to textbook descriptions of baroque painting: in a phrase, strong directional light. But look closely at a painting like The Calling of St Matthew by Caravaggio. A single shaft of light strikes the figures at the table. But hovering in the darkest corner are four anomalies of light: the two suspended hands of the ‘callers’ (the left hand of one, the right hand of the other), one caller’s face and the cloaked back of the second. A monstrous creature.

The general procedure is simple. The painter applies just enough poetic-luminous license in order to pick out the necessary details - faces, hands, insignia etc. But the greatest Baroque painters go much further. In Rembrandt, light is the light of the soul and the soul lives in the flesh. Hence light emanates from bodies. A hand, a face, a torso lights up its surroundings, and this light will be snuffed out the moment the body perishes. In Velazquez light is more diffuse (pale and silvery) but is never universal. The light in his large compositions is often transmitted via a series of frames: windows, doors, mirrors and pictures within pictures. There is a nesting of images, a waterfall of mirrors.

Is it coincidence that Baroque painting or the Golden Age coincides with the Scientific Revolution? In the last fragment from One Way Street, titled ‘To the Planetarium’, Walter Benjamin describes how "the exclusive emphasis on an optical connection with the universe", as pursued by the great astronomers of the late 16th to early 17th century - Kepler, Copernicus, Tycho Brahe - enacted a quantum leap in the progressive disenchantment of the world. And yet the pictorial equivalent of this paradigm shift was not perspective (discovered much earlier), but chiaroscuro. Not the all embracing grid stretching to infinity, but rather a shallow space, shuttered and contorted. A lime-washed, silver-coated light ricocheting throughout the space. What modern astronomers have in common with baroque painters is a similar relationship to the subject. The Copernican subject doubts its own position. Its method of observation is indirect, transmitted via the prism of an abstract model. And the knowledge gained contradicts direct experience. The earth is not the centre of the universe. The subject’s position must be taken account of precisely in order to discount it.

According to Benjamin the ancient Greeks related to the cosmos with a kind of intimacy "scarcely known to later periods".⁷ Georg Lukács suggested something similar in his discussion of epic literature. In the epic "the world is wide and yet it is like a home, for the fire that burns in the soul is of the same essential nature as the stars; the world and the self, the light and the fire, are sharply distinct, yet they never become permanent strangers to one another, for fire is the soul of all light and all fire clothes itself in light. Thus each action of the soul becomes rounded in this duality".⁸ The subject of the epic is not to be confused with the schizoid subject of postmodernity; it is too centred for 21st century tastes. Its heroism, its self-sufficiency - the ability to act in the world - draws its power from the more or less immediate resonance of individual action and wider totality.

Lukács assumed that this mode of experience passed away a long time ago. He never anticipated that the dialectic of modernity might one day resurrect it. Which is precisely what Benjamin saw happening in the First World War and the revolutions of 1917-18: "a new and unprecedented commingling with the cosmic powers", in which "human multitudes, gases, electrical forces were hurled into the open country, high frequency currents coursed through the landscape, new constellations rose in the sky, aerial space and ocean depths thundered with propellers and everywhere sacrificial shafts were dug in mother earth." But the project of a new epic was thwarted, or turned perverse in the very moment it became manifest. Humanity’s betrayal of nature - and of itself - "turned the bridal bed into a blood bath."⁹

And yet in the moment before potentiality becomes actuality there remains this promise: a face glowing in the darkness, the image of human intelligence. The image continues to haunt us. But a face lit by a candle, or better, by the indiscernible light of the soul, is different from a face lit by a screen. The shifting colours of a plasma screen, or the blue glow of an LCD, reflect the static impulses of a vast cloud of information, a "cosmic network of rails",¹⁰ a truly planetary order. It is an order dominated by capital and in that sense no different from any other sphere of modern experience (a street, a home, a city etc.). And yet at the same time it holds out the promise of universal communion.

Two images: chiaroscuro and screen light. The gap between the two can be measured in years, about 350 of them. This is the distance between the Scientific Revolution and the electronic one, between the dawn of modern experience in the 17th century and late modernist experience towards the end of the 20th. The same minimal gap separates the experience of the lonely traveller who catches sight of a lighted window and the city wanderer whose path follows the trail of street lamps stretching into the distance, apparently endless. The traveller - pilgrim, journeyman, or petty trader - takes the lamp hanging on a gate as a sign, a promise, of shelter and hospitality. A street light, or a pair of headlamps on a motorway, or indeed a light in a window - this time arrayed in a grid with hundreds of others - is also a promise. Compared to the lamp on the gate or the fire in the hearth it promises both much more and much less. More because mass experience converts conviviality, hospitality etc. into collective joy and collective solidarity. Less because the same experience tends to render these things impossible, in other words utopian. Likewise our everyday pilgrimages are so much more and so much less than the old pilgrim’s journey. They are a search for universal communion and at the same time drudgery, a slow march going in circles.

Hence the role of lonely city wanderer that Walter Benjamin so often cast himself in, is at one and the same time the replica and the inverse of the cab driver in revolutionary Petrograd, who stretches out his arm across the glittering horizon, to proclaim ‘ours, all ours’. Alienation is the degree zero that makes revolutionary mass experience possible. Artificial light is a touchstone for both.