Oliver Sacks: 'We are more likely to see UFOs when our forebears would see angels'

In writing about hallucinations, you mention your own experience since losing the sight of one eye to ocular cancer of "seeing things". How much has your curiosity about hallucination been heightened by such "visions"?

It has been, certainly. Since my illness, If I look at the ceiling I sometimes see geometric forms, mostly letters and numbers of different kinds. To begin with, I was startled like anyone who sees things they believe aren't out there in the real world, and these patterns appeared all over my visual field. Then I became fascinated by the detail of some of them but now my brain mostly ignores them in the way that it ignores my tinnitus, which is also a constant, but only there when I remind myself to hear it.

I guess we all filter some aspects of perception out in order to make sense of the world. Do you think that we restrict ourselves to a narrow range of reality?

If we scrutinised everything we perceive all the time more carefully, then we would be overwhelmed by attention. One realises in a way how narrow ordinary consciousness is, but necessarily so if one is going to function in the world. If there is a huge enhancement of perception, as there is with certain kinds of minds, it is hard to get along very easily.

If we are always actively filtering out large parts of what we see and hear, it begs the question of what our sense of reality consists of?

It does, though I would also say that some of the kinds of hallucinations I describe in the book are more extreme than others. It is a normal brain function to filter out the noise of tinnitus, for example, but if you see a three-foot goblin a few yards away at the end of your bed – as some people who hallucinate do – you are probably going to struggle to ignore it.

It seems that such visual disorders at certain points in history have been more "believable" and also, therefore, more commonly noted?

Yes, in other places and at other times, hallucinations were far more acceptable. Up to about 1800, people were allowed to have visions or to hear voices. They were seen to have some external spiritual reality; they were ghosts or angels or demons. The word hallucination only really became a pejorative at the end of the 18th or early 19th century. We still associate it with madness. But how those who hallucinate understand what they see also changes. We are more likely to see UFOs and aliens when people in earlier times would see angels.

I guess in a way we still "license" certain people to be visionaries. We like the idea of our poets and artists having fevered imaginations and are enthralled by the kinds of altered consciousness they might describe.

I know a few poets and the idea that the words come to them, as if from an external force or a muse, remains very strong. And of course poets such as William Blake were obviously describing hallucinatory experiences of quite extreme kinds, similarly someone such as Dostoevsky. Artists and painters and even some scientific discoveries have come from not what we would describe as rational consciousness but some other dreamlike or hallucinatory state.

Do you feel that mystery about your own writing even?

I do to a degree. I mean, I never start a sentence really knowing how I am going to finish it, and I only discover my intentions as I write. I have kept a journal quite obsessively since I was 14 or so, not for publication in any way, just talking to myself really, listening to myself. I keep them all of them in boxes still.

Do you go back to them?

Very rarely. Though it so happens that a few weeks ago I opened a box from 1950, and I found a journal which was my farewell to Europe, my expereince of leaving home in England and my first days in America, full of that sort of exciting honeymoon feeling of discovery.

When you read it now does it seem your own voice?

Yes and no. When I read that one I was rather shocked to find I didn't much like my earlier self. In a letter Freud wrote in his late 60s, he said he found it difficult to identify with a young man who once kept up a nervous vigil at a train station but he supposed it must have been him. I feel something the same about my own life.

In the book, you write frankly about your efforts to alter your own consciousness with drugs of all kinds in the 1960s. Was the motivation scientific curiosity or a more pressing psychological necessity?

It was a definite need. I was ravenous for the sort of experience that, if nothing else, would give me pleasure, but hopefully would stimulate the imagination and intellect and get me going again. I had a very strong heightened intellectual sense in my early adolescence, which I felt had deserted me after university, and I wanted to do anything to have it return. I wanted to shake myself up and open a new chapter and drugs seemed one way of doing that. And I think it worked to a degree, though of course there were enormous risks.

In the end, as you say, you were lucky that writing cured you of that need.

Yes, from my late teens on I was loving language and needing to write, although not sure what to write about. In a notebook, when I was 23 or 24, I set down my intention to write five novels. I didn't and I stand in awe of novelists who can give these alternative autonomous realities life and credibility. But I wanted to be a storyteller and I found a way of doing that eventually with elaborate case history. I mourn what is really the passing of that method in favour of diagnostics, which causes doctors to simply tick off criteria without ever once describing a particular patient in detail.

That book also proved that stories are the fundamental way in which we make sense of the strangeness of the world.

Yes. The folklore of every culture is full of such explanations. In terms of hallucinations, whether associated with migraine, or epilepsy, or grief, or any other cause, we tell stories. Each culture has tales of little beings, elves and fairies and whatever. Lilliputian hallucinations are among the most common, in fact. And if you are Irish, you will see them as leprechauns and Norwegian as trolls.

You make clear in the book how easily those vivid imaginative states can take on a religious or spiritual impulse. Have you ever felt that impulse yourself?

No, I think I have had the storytelling impulse itself all my life, but it didn't too often take a mystical or religious turn. I came from a very Jewish orthodox family and when I would watch my mother huddle over a candle and murmur a prayer to welcome the sabbath, there was a strong feeling of the peace of God and I imagined that the sabbath was a sort of cosmic event and tranquillity would settle on millions of planets right across the universe. It hasn't really happened to me since.

One effect of your work has been to give you access to an endless supply of other people's stories through the mail. It sounds like you get new case studies every day almost.

I do. In fact, when you phoned, I was halfway through a letter, with some very interesting thoughts on the locked-in syndrome I described in Awakenings. I spend three hours a day on correspondence. I don't use email for that; if I want to respond I respond by hand. As I get older and can physically see fewer patients, this younger network of correspondents nourishes me.