It had not occurred to me for an instant that Jim and Kathy’s voices, their “presences,” were unreal, hallucinatory. We had had a friendly, ordinary conversation, just as we usually had. Their voices were the same as always—there was no hint, until I opened the swinging doors and found the living room empty, that the whole conversation, at least their side of it, had been invented by my brain.

I was not only shocked but rather frightened, too. With LSD and other drugs, I knew what was happening. The world would look different, feel different, there would be every characteristic of a special, extreme mode of experience. But my “conversation” with Jim and Kathy had no special quality; it was entirely commonplace, with nothing to mark it as a hallucination. I thought about schizophrenics conversing with their “voices,” but typically the voices of schizophrenia are mocking or accusing, not talking about ham and eggs and the weather.

“Careful, Oliver,” I said to myself. “Take yourself in hand. Don’t let this happen again.” Sunk in thought, I slowly ate my ham and eggs (Jim and Kathy’s, too) and then decided to go down to the beach, where I would see the real Jim and Kathy and all my friends, and enjoy a swim and an idle afternoon.

I was pondering all this when I became conscious of a whirring noise above me. It puzzled me for a moment, and then I realized that it was a helicopter preparing to descend, and that it contained my parents, who, wanting to make a surprise visit, had flown in from London and, arriving in Los Angeles, had chartered a helicopter to bring them to Topanga Canyon. I rushed into the bathroom, had a quick shower, and put on a clean shirt and pants—the most I could do in the three or four minutes before they arrived. The throb of the engine was almost deafeningly loud, so I knew that the helicopter must have landed on the flat rock beside my house. I raced out, excitedly, to greet my parents—but the rock was empty, there was no helicopter in sight, and the huge pulsing noise of its engine was abruptly cut off. The silence and emptiness, the disappointment, reduced me to tears. I had been so joyful, and now there was nothing at all.

I went back into the house and put on the kettle for another cup of tea, when my attention was caught by a spider on the kitchen wall. As I drew nearer to look at it, the spider called out, “Hello!” It did not seem at all strange to me that a spider should say hello (any more than it seemed strange to Alice when the White Rabbit spoke). I said, “Hello, yourself,” and with this we started a conversation, mostly on rather technical matters of analytic philosophy. Perhaps this direction was suggested by the spider’s opening comment: did I think that Bertrand Russell had exploded Frege’s paradox? Or perhaps it was its voice—pointed, incisive, and just like Russell’s voice, which I had heard on the radio. (Decades later, I mentioned the spider’s Russellian tendencies to my friend Tom Eisner, an entomologist; he nodded sagely and said, “Yes, I know the species.”)

During the week, I would avoid drugs, working as a resident at U.C.L.A.’s neurology department. I was amazed and moved, as I had been as a medical student in London, by the range of patients’ neurological experiences, and I found that I could not comprehend these sufficiently, or come to terms with them emotionally, unless I attempted to describe or transcribe them. It was then that I wrote my first published papers and my first book. (It was never published, because I lost the manuscript.)

But on the weekends I often experimented with drugs. I recall vividly one episode in which a magical color appeared to me. I had been taught, as a child, that there were seven colors in the spectrum, including indigo. (Newton had chosen these, somewhat arbitrarily, by analogy with the seven notes of the musical scale.) But few people agree on what “indigo” is.

I had long wanted to see “true” indigo, and thought that drugs might be the way to do this. So one sunny Saturday in 1964 I developed a pharmacologic launchpad consisting of a base of amphetamine (for general arousal), LSD (for hallucinogenic intensity), and a touch of cannabis (for a little added delirium). About twenty minutes after taking this, I faced a white wall and exclaimed, “I want to see indigo now—now!”

And then, as if thrown by a giant paintbrush, there appeared a huge, trembling, pear-shaped blob of the purest indigo. Luminous, numinous, it filled me with rapture: it was the color of heaven, the color, I thought, that Giotto spent a lifetime trying to get but never achieved—never achieved, perhaps, because the color of heaven is not to be seen on earth. But it existed once, I thought—it was the color of the Paleozoic sea, the color the ocean used to be. I leaned toward it in a sort of ecstasy. And then it suddenly disappeared, leaving me with an overwhelming sense of loss and sadness that it had been snatched away. But I consoled myself: yes, indigo exists, and it can be conjured up in the brain.

For months afterward, I searched for indigo. I turned over little stones and rocks near my house. I looked at specimens of azurite in the natural-history museum—but even that was infinitely far from the color I had seen. And then, in 1965, when I had moved to New York, I went to a concert at the Metropolitan Museum of Art. In the first half, a Monteverdi piece was performed, and I was transported. I had taken no drugs, but I felt a glorious river of music, hundreds of years long, flowing from Monteverdi’s mind into my own. In this ecstatic mood, I wandered out during the intermission and looked at the objects on display in the Egyptian galleries—lapis-lazuli amulets, jewelry, and so forth—and I was enchanted to see glints of indigo. I thought, Thank God, it really exists!

During the second half of the concert, I got a bit bored and restless, but I consoled myself, knowing that I could go out and take a “sip” of indigo afterward. It would be there, waiting for me. But, when I went out to look at the gallery after the concert was finished, I could see only blue and purple and mauve and puce—no indigo. That was forty-seven years ago, and I have never seen indigo again.

When a friend and colleague of my parents—Augusta Bonnard, a psychoanalyst—came to Los Angeles for a year’s sabbatical in 1964, it was natural that we should meet. I invited her to my little house in Topanga Canyon, and we had a genial dinner together. Over coffee and cigarettes (Augusta was a chain-smoker; I wondered if she smoked even during analytic sessions), her tone changed, and she said, in her gruff, smoke-thickened voice, “You need help, Oliver. You’re in trouble.”

“Nonsense,” I replied. “I enjoy life. I have no complaints. All is well in work and love.” Augusta let out a skeptical grunt, but did not push the matter further.

I had started taking LSD at this point, and if that was not available I would take morning-glory seeds instead. (This was before morning-glory seeds were treated with pesticide, as they are now, to prevent drug abuse.) Sunday mornings were usually my drug time, and it must have been two or three months after meeting Augusta that I took a hefty dose of Heavenly Blue morning-glory seeds. The seeds were jet black and of agate-like hardness, so I pulverized them with a mortar and pestle and then mixed them with vanilla ice cream. About twenty minutes after eating this, I felt an intense nausea, but when it subsided I found myself in a realm of paradisiacal stillness and beauty, a realm outside time, which was rudely broken into by a taxi grinding and backfiring its way up the steep trail to my house. An elderly woman got out of the taxi, and, galvanized into action, I ran toward her, shouting, “I know who you are—you are a replica of Augusta Bonnard! You look like her, you have her posture and movements, but you are not her. I am not deceived for a moment.” Augusta raised her hands to her temples and said, “Oy! This is worse than I realized.” She got back into the taxi, and took off without another word.

We had plenty to talk about the next time we met. My failure to recognize her, my seeing her as a “replica,” she thought, was a complex form of defense, a dissociation that could only be called psychotic. I disagreed and maintained that my seeing her as a duplicate or impostor was neurological in origin, a disconnection between perception and feelings. The ability to identify (which was intact) was not accompanied by the appropriate feeling of warmth and familiarity, and it was this contradiction that led to the logical though absurd conclusion that she was a “duplicate.” (This condition, which can occur in schizophrenia, but also with dementia or delirium, is known as Capgras syndrome.) Augusta said that, whichever view was correct, taking mind-altering drugs every weekend, alone, and in high doses, surely testified to some intense inner needs or conflicts, and that I should explore these with a therapist. In retrospect, I am sure she was right, and I began seeing an analyst a year later.

The summer of 1965 was a sort of in-between time: I had completed my residency at U.C.L.A. and had left California, but I had three months ahead of me before taking up a research fellowship in New York. This should have been a time of delicious freedom, a wonderful and needed holiday after the sixty- and sometimes eighty-hour work weeks I had had at U.C.L.A. But I did not feel free. When I am not working, I get unmoored, have a sense of emptiness and structurelessness. Weekends were the danger times, the drug times, when I lived in California—and now an entire summer in my home town, London, stretched before me like a three-month-long weekend.

It was during this idle, mischievous time that I descended deeper into drug-taking, no longer confining it to weekends. I tried intravenous injection, which I had never done before. My parents, both physicians, were away, and, having the house to myself, I decided to explore the drug cabinet in their surgery, on the ground floor of our house, for something special to celebrate my thirty-second birthday. I had never taken morphine or any opiates before. I used a large syringe—why bother with piddling doses? And, after settling myself comfortably in bed, I drew up the contents of several vials, plunged the needle into a vein, and injected the morphine very slowly.

Within a minute or so, my attention was drawn to a sort of commotion on the sleeve of my dressing gown, which hung on the door. I gazed intently at this, and as I did so it resolved itself into a miniature but microscopically detailed battle scene. I could see silken tents of different colors, the largest of which was flying a royal pennant. There were gaily caparisoned horses, soldiers on horseback, their armor glinting in the sun, and men with longbows. I saw pipers with long silver pipes, raising these to their mouths, and then, very faintly, I heard their piping, too. I saw hundreds, thousands of men—two armies, two nations—preparing to do battle. I lost all sense of this being a spot on the sleeve of my dressing gown, or the fact that I was lying in bed, that I was in London, that it was 1965. Before shooting up the morphine, I had been reading Froissart’s “Chronicles” and “Henry V,” and now these became conflated in my hallucination. I realized that I was gazing at Agincourt, late in 1415, and looking down on the serried armies of England and France drawn up to do battle. And in the great pennanted tent, I knew, was Henry V himself. I had no sense that I was imagining or hallucinating any of this; what I saw was actual, real.