Perhaps it’s memory. Most people, I guess, quickly forget what they’ve read, what they’ve seen. Dad and Becky both said something like: even your average film buff forgets how most movies end. That’s a comfort. Or is it? I’ve heard somewhere about how fallible are the memories of witnesses to a crime scene. Why is memory, which is so good, so necessary and useful, also so bad?

I’m returning on a train to London, and I’m being lulled into a half-slumber, a mixture of memory and dream. I can feel the chill glass against my head. I can hear the clamour of the train, a muffled, repetitive sound, industrial, grimy. I’m aware of this and of someone’s elbows beside me. Yet I’m also dreaming, out of control, in a way that’s beyond daydream, more phantasmagoric. Kids brush past me on bicycles and it’s raining wet soot. My father tells me I’m in a lunatic asylum and Becky the rat-catcher is in a doctor’s white coat telling me that if I don’t remember who I am I’ll stay on Portsea Island. I think about the proximate Isle of Wight, which I’ve never been to, but I know there’s a prison there. Then I’m in a college library…

I’ve heard somewhere about how fallible are the memories of witnesses to a crime scene. Why is memory, which is so good, so necessary and useful, also so bad?

I snap out of the reverie, shaken. I cannot remember having had such an experience. Becky insisted that Shutter Island is not just about madness — the more you revisit it, she said, the more it becomes a true horror, drawing you into madness. Can a film be that good, that awful?

On the tube from Waterloo to St. John’s Wood I’ve returned more or less to normal, though now I’ve switched from memory to thinking about madness. I know that’s a loose word, which refers to terrible mental conditions. Mad people are sociopaths, dangerous, antisocial, but even this is vague and inadequate.

I know next to nothing, and most (horror!) people know next to nothing. Yet we must make up our minds. It’s a credo of mine that to be a person at all, and not mere animated fluff, one must make up one’s mind. The question therefore is not “What is madness?”, but “What is madness as I see it?”

I get out into the air at St. John’s Wood and walk to my flat, still not knowing what I think madness is, and beginning to be afraid to know, feeling like I’m in a rat’s maze, one where the reward is poison. To console myself, I half-decide it may be lack of restraint (plus frenzy or delusion).

Which will have to do.