Presently, a new kind of antidepressant came along, the SSRI, with a seemingly more benign side-effect profile than the older antidepressants, such as amitriptyline, which was dangerous in the overdoses that the depressed, or so-called depressed, were inclined to take. And the SSRIs came with a pleasingly simple hypothesis to explain their efficacy, insofar as they had any. A real bonanza! Before long, a sixth of the adult population of several large countries were taking them. A pill for every ill became a social, if not strictly a medical, reality. The sum total of human misery is difficult to measure, but it is not obvious that it has declined with the advent of these drugs.

The theory proved popular with the public, which could now account for its discontent by reference to chemical imbalance in the brain, though much of that public would be hard put to distinguish potassium permanganate from copper sulphate. It gave people license to talk about themselves without revealing anything. I have overhead many conversations in buses, trains, and elsewhere about the chemical imbalance in one of the interlocutor's brains. It is not me; it is my neurotransmitters. And insofar as the SSRIs, like so many medicines, exert a powerful placebo effect in addition to a true therapeutic effect, the theory seemed in many cases to be vindicated.

The whole question of human misery is fearsomely complex. But what else should we expect? We thirst for simplification as a voyager in the desert thirsts for water.