Greene used to sort his own books for you, right on the title page: this one a novel, that one an entertainment. The thrillers went in the second pile — Stamboul Train, The Ministry of Fear, Our Man in Havana — and the ones he meant you to sit still for stood apart. He let the distinction go eventually; in the later collected editions it just isn't there any more, and I've always read that as a man deciding the two shelves were one shelf after all and had been for years.
Which is roughly what happens in a shop anyway. I put him in alphabetically and the sorting undoes itself; somebody comes in for the Havana one because of the vacuum cleaner salesman and leaves with The Quiet American, and I'd be the last to tell them they've made a category error. I have two copies of Brighton Rock. One has been read until the spine gave; the other looks like it was bought as homework and let off.
And the openings. "Hale knew, before he had been in Brighton three hours, that they meant to murder him" — that's the whole machine assembled in one line, the clock already running, and you can't put the book down because you've already started counting. He was born in Berkhamsted in 1904, where his father taught at the school he'd later attend; I don't know what that does to a boy, but the sentences come out watchful.
Jun, he kept that same refusal to sort in his religion: he called himself a Catholic agnostic late on, and in the novels the doctrine is always in somebody's mouth, never the narrator's. The whisky priest is allowed to be wrong, and nobody arrives to correct him.
The Third Man came to him as a treatment first — he said he couldn't write a screenplay cold, so he wrote it as prose and then took it apart. And the zither: Karas was playing in a Vienna wine tavern when Reed heard him, and the whole score came out of that one instrument.