The Noonday Demon: An Anatomy of Depression
Andrew Solomon
(Vintage, £8.99)

Bad advice about how to cope with depression abounds. One comparatively helpful article in a Singapore magazine, although of a tenor not necessarily confined to Asia, ran: "Seek professional help if you need it, but in the meantime, cheer up." This, for many, is not an option. You might live in Greenland, where 80 per cent of the population suffers from depression, and where, in winter, as one Inuit put it, "we all sat around together for months watching the walls melt." (The prime suicide month in Greenland, interestingly, is May.) Heredity - not having depressed parents - helps; so does heterosexuality, and the good fortune to avoid major trauma. Another recipe, apart from not living anywhere near the Arctic Circle, is to have what is winningly, and indeed tellingly, called a "good enough" marriage.

Good books about depression, though, do abound. Between Robert Burton's 17th-century The Anatomy of Melancholy and Lewis Wolpert's Malignant Sadness (1999) - both previous paperbacks of the week - the field grows, in acknowledgment of the quiet crisis afflicting anything up to 10 per cent of the population. Or maybe more.

And by depression we do not mean the dumps, which in my experience can be at least temporarily allayed by a cup of tea and a fag, but something much further up the scale, whose symptoms include the bleakest despair, uncontrollable vomiting, total withdrawal from society, and self-mutilation. In Solomon's case, this took the form of reckless midnight sexual encounters with strangers who, he hoped, would pass on their HIV. (Luckily, he didn't get it.)

For Solomon knows whereof he speaks. The book's honesty is both fuelled and exemplified by his accounts of his own major depressive episodes, which are by no means self-indulgent but allow fellow-sufferers to know they are not alone, and allow non-sufferers to gain some idea of the agony of the condition. (It is difficult, he points out, to get depressives to meet and discuss their illness, as they're often too depressed to get out of bed; moreover, the depressed are, in his phrase, "incompetent lobbyists", so it is hard to get the condition onto the political health-care agenda.)

Solomon has done his work. Depression, he shows us, has been known to humanity from the beginning; it was known to the Psalmist, from whom he gets the title of the book. Not only is it not a modern disease; it is not confined to the wealthy and whiny middle classes. The poor are more likely to suffer, and they are also more likely to be unable to do anything about it. Shame about the condition affects the well-off; but it affects the poor more.

This, to my knowledge, is now the definitive lay text on the subject. Solomon charts the history, the science, and even the philosophy of depression with an industry and thoroughness that must have been hell for him to achieve. A mild warning: although this is by no means a book whose readership should be confined to the truly depressed, or those who know and care for them, the warily healthy should brace themselves when reading it. I cantered through the first 100 or so pages - it is a very well-written book, not without humour - feeling progressively more chipper: I found my suspicion that I do not suffer unduly from depression increasingly confirmed. However, as Solomon himself says at one point, those who read The Noonday Demon carefully will learn how to be depressed. But that's no reason not to read it. Knowledge, in this instance, is most certainly power.