The most useful thing I learned in an 18 year education was that a white sheet of paper is never white. I learned this by spending five full days staring at an unmarked A1 sheet pinned to a wall, trying at first to draw, and then to paint it. The exercise was set by one of the most miserable teachers I ever had, a failed painter who wanted to be home on the north coast of Cornwall and not in the center of probably the ugliest and most landlocked city in Britain. For the whole five days he gave no instruction. He walked up to me from time to time, shook his head, laughed and moved on. I think he did ask at one point if it hurt me to use my brain. Nevertheless, the exercise was a revelation, the visual version of meditating on a Koan. If you look hard enough, you start to see things which can never be unseen. A white sheet of paper is a kind of mirror, it takes on the colours of everything that surrounds it.

It took me a very long time to be able to sleep in darkness. I would never permit my parents to close my bedroom door, the light on the landing had to be on and the door fully open all night. Some nights they would close it when I was asleep but I was so tuned into the click of the latch that it instantly woke me up and I got up to open the door again. Later I rigged up a contraption with wires so I could turn the handle and open the door without getting out of bed. Darkness is like a white sheet of paper, it takes on the shapes of everything that surrounds it. I went to a sink school. I was deeply introverted and isolated. My father was difficult, a compulsive gambler and a depressive. Sometimes when I sat on my bed the floor would drop away, hundreds of feet down. I didn’t talk to anyone so the anxiety attacked after dark, taking on shapes and voices.

I’m now lucky enough to live in a place where I can experience natural sound some of the time, the acoustics of weather and animals removed from the constant hum of engines and electronic noise that accompanies our lives in most places. The hour after dark is the best time to experience it. Hilltops and green mountains are the best places, where everything above is sky and the ground below is soft turf. Sometimes I’ll try to approach a herd of wild horses, their grazing shapes indistinct, only just visible as humps above the high bracken. I’ll walk very slowly, trying not to make a noise. Horses have 350-degree vision and can see very well at night, but they don’t expect to encounter humans out walking after dark so they are not as alert as in the daytime. But sooner or later they sense me, their heads shoot up and I hear their breathing deepen. They spook and burst into a gallop. I can feel the drumming of their hooves as if it were my heartbeat.  A horse’s eye contains a darkness I’ve never witnessed in any other creature. The slot of its pupil floats on fathoms of black water containing a history more tragic than any other species except our own. A horse’s eye expresses mourning deeper than a wolf’s howl.

Years ago in a place where the sun plunged rather than set, day turning into night as if a bulb has blown. The smell of half-rotten mangoes and bananas. I’m sitting on a pile of maize sacks with a group of people crammed into an open-backed truck. No-one is speaking. We stop at a place unmarked on the map, a village without electricity, high mud walls, a single dirt road. I jump out and walk a hundred meters, through drifting wood smoke. I turn round and my fellow passengers have disappeared, the truck headed back in the other direction. That post dark silence coming out of the forest like a fog. I stumble on the ruts in the road. I can just make out the tops of the trees against the deep night. I’m completely lost, without food or water, unable to speak the local language. There is no shop, bar or hotel. I walk back to where the truck stopped, feeling my way, hearing the click of bicycle wheels up ahead. Then a hand grabs mine and pulls me into an alleyway. A gate opens and there is the square of a window, flickering with candlelight. An old woman, less than five feet tall is smiling up at me, pointing me to a doorway. She props the bike against a wall and beckons me forward. Inside are a dozen people, children of all ages, a couple of women in their twenties. They sit me down, pour tea from a kettle fetched from an open fire in the yard. The children, giggling wildly, stalk up to me and touch my hair, scream, run and hide behind their grandmother. She tells them off. She fills a bowl with water and heats it on the fire so I can wash. All evening we try to communicate, miming, pointing. We manage to repeat each other’s names. She is called Atiena. Years later I look the name up. It means Guardian of the Night. Eventually, she leads me to a large room which is filled with beds with barely any space between them. She leaves me a jug of water and a candle. I lie listening to mice skittering across the floor and eventually I fall asleep. I wake early, the sun bright through the rag curtained window. When I open the door onto the yard all of the family, including the old woman, are asleep, lying on the ground. They have let me, a total stranger from a place halfway across the planet, sleep in their only bedroom. This was the Eastern Congo. A few months later I would fly home to England while a war broke out in those hills, more vicious than any in African history, where women and children would be the main victims. I will never know what happened to Atiena in that heart of darkness.

The nocturnal bottleneck theory suggests that most mammals in their early evolution had good colour vision and high acuity of sight. These traits were lost as they went through the Mesozoic where they were forced to avoid the predation of day-active dinosaurs and therefore, as a survival strategy, became nocturnal. This adaptation remains in the eye structures of most mammals to this day. The only species that don’t show this trait are humans, monkeys and apes. The hour after dark is when the page goes blank for us. It’s when we’re at our most vulnerable. It’s when the senses we mostly ignore in the day become more acute. Cold air brushing the skin, the scent of fallen apples, the distant sound of a woman’s voice as she calls through an open window. It is not necessarily the time when stories are composed, but it is the time they arrive in us.

Cloud is crossing the sky, the moon and stars slide into their drawers. The blue glow that illuminated the lanes between the bracken has disappeared and I still have a mile or more to go. My landmark now is the sulphur glow above Hereford and the little clusters of light from the villages below in the valley. I can hear my dog panting as she chases rabbits. Occasionally, if I don’t look for her, I see her in the tail of my eye. Colours and shapes appear. Two snipe are calling, one north and close by, one south and distant. Between the alternating, high pitched notes there are voices.