What We See in the Shadows

Written By Virginia Ziulu

All That Emerges When the Light Recedes

There is a very old story about an underground cavern. The room is dark. A group of prisoners sits inside, their bodies chained so that they can see only the wall before them. Behind them burns a fire. Between the fire and the prisoners, others carry objects whose shadows are projected onto the wall. The prisoners have known nothing else. So they take the shadows for reality. They watch them pass across the wall. They give them names. They make a world of them.

This is no ordinary cave, of course. It is a fictional one, described by Plato in his Allegory of the Cave. And, as Plato tells it, it is a world sustained by ignorance and deception.

More than two thousand years later, shadows still carry a certain disrepute. We expose shadowy dealings. We speak of shadow governments, shadow economies, and shadow organisations. We describe suspicious figures as shadowy. We talk about becoming a shadow of our former selves or living in someone else's shadow.

And if living in someone's shadow is already an act of surrender, Jacques Brel carries that surrender somewhere darker. Almost to the point of self-erasure. In Ne Me Quitte Pas (Don't Leave Me), he begs his beloved to let him become the shadow of her shadow, the shadow of her hand, even the shadow of her dog. To live in her shadow is not enough. He wishes to disappear into hers: always present, always following.

 

The pattern is hard to miss. What is in the light is legitimate. What remains in the shadow is suspect. But shadows have many more stories to tell. And science has found ways to read them. Not as diminished versions of reality, but as evidence of it. And sometimes, even as something worth preserving.

It turns out that a shadow can tell us quite a lot about the thing that casts it, even across astonishing distances. Aristotle noticed that during a lunar eclipse, the shadow cast by the Earth on the Moon was always curved, an observation he used as evidence that the Earth was spherical. A few centuries later, Aristarchus of Samos went further. By observing the geometry of the Earth's shadow during a lunar eclipse, he reasoned that it was possible to estimate the size of the Earth. A shadow could become a measuring instrument. And the same idea works much closer to home. Look straight down at a building or tree, and its height largely disappears from the image. But let it cast a shadow, and that shadow becomes a ruler. Measure the shadow, know the position of the Sun, and the height can be estimated. The Earth, a building, a tree: the principle is the same.

A shadow can also reveal what lies hidden. In aerial archaeology, for example, subtle variations in ground elevation associated with buried structures can become visible in the shadows produced by low-angle sunlight. The structure itself may be fully hidden beneath the ground, but shadows can reveal its presence in the landscape above it.

Sometimes it is the object that disappears … but its shadow lingers. Thermal imagery can capture what is sometimes called a ghost imprint—a fleeting trace of something that has just disappeared. An aircraft that has left the tarmac may leave behind a cooler patch where it had shielded the surface from the Sun. The aircraft is gone. For a little while, its shadow remains.

Yet other times, to see what has changed, we need the shadows to remain unchanged. Many imaging satellites are placed in sun-synchronous orbits, passing over locations at approximately consistent local solar times. This keeps illumination—and therefore the shadows—relatively consistent from one image to the next. When the shadows fall in similar directions and proportions, changes in the landscape become easier to see. Shadows become part of the conditions that allow change to reveal itself.

 

Strange, isn't it, how much a shadow can become? But shadows are capable of stranger things still. Science is not the only discipline to have wondered what happens in the shadows.

Some shadows we do not choose. These are not shadows cast against a wall, or across a landscape. They are shadows that slowly enter a life. Jorge Luis Borges knew them well. In Elogio de la Sombra (In Praise of the Shadow) he writes from the penumbra of old age and blindness. The visible world recedes. Faces disappear. Streets become indistinct. The letters on the pages of books can no longer be read.

And yet the penumbra does not seem to trouble Borges. It is slow, painless, almost kind.  As the world around him becomes smaller, something inward seems to become clearer. “There were always too many things in my life,” he writes. “The animal has died, or almost died; the man and his soul remain.” The paths of a lifetime now converge on what he calls his secret centre. The shadow takes things away. But what remains is not emptiness. It is room for what is essential.

But there are other ways into the shadows. Gentler ones. The Japanese novelist Jun'ichirō Tanizaki wrote an entire essay in their defence, In Praise of Shadows. We have long left behind the dark underground cave. We are now in a dimly lit Japanese room. Plain wood, neutral walls, muted colours, paper screens, sparse objects. In the half-light, the room is anything but empty. Heavy shadows meet lighter ones. The spaces between objects acquire depth and even beauty. Even emptiness can have presence. For Tanizaki, this is the magic of shadows.  

We have grown rather fond of light. Our world is now one of excessive illumination. There is the light for reading, the light for cooking, the light for sewing. And then there is the other light... the light we turn on simply because we do not want the room to be dark. The light that banishes the last shadows, almost as if we cannot bear even the smallest patch of darkness. Tanizaki's answer is almost a provocation: turn off the lights.

We spend so much time trying to step out of the shadows.

Perhaps, at least this once, we might stay for a moment.

Let the shadows return.

And see what emerges.

 

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