BOOK REVIEW / In sooth we know not why he's sad: 'Depression and how to Survive it' - Spike Milligan and Anthony Clare: Ebury Press, 14.99 pounds

SPIKE MILLIGAN is Britain's best known manic depressive and Anthony Clare is Britain's best known psychiatrist. They have combined their talents to produce a sort of layman's guide to the illness. Milligan talks about himself, while Clare talks about depression and uses Milligan as an anatomist might use a cadaver, listing the possible causes of his illness one by one.

'The Milligan family tree,' he begins, 'has its fair share of disturbed branches.' Which family tree hasn't? He had a domineering and possessive mother. Who didn't? His father - a regular soldier - was often away. Millions have no father at all. He didn't get on with his brother. He sired an illegitimate son. He missed his scenes of childhood. He . . .

Clare devotes an entire chapter to manic depression and creativity. The inevitable names crop up - Goethe, Nietszche, Blake, Van Gogh, Gogol, Swift, Ruskin, Strindberg, Kafka, Schuman, Tchaikovsky - as if bouts of insanity are a necessary price of genius. It may be reassuring for manic depressives to find themselves in such company, but we know about the disorders of the famous, partly because they usually have the leisure to dwell on their disorders, and partly because they have the powers of expression to describe them. There are great artists who have lived normal, happy lives; there are any number of people who are not particularly talented but who are deeply depressed. Clare suggests that Milligan's creativity may have been helped by 'elevated mood swings', but he does not consider the possibility that his success as a clown is due, in part, to the relief which can be found in clowning.

I once had to cover a reunion of concentration-camp survivors. Given what they had been through, they had ample cause for madness, but they were nearly all refreshingly sane. It seemed to me then that one cannot explain mental disorders in terms of this or that trauma, and this book has confirmed my view. As Shakespeare put it: In sooth I know not why I am so sad:

It wearies me; you say it wearies you;

But how I caught it, found it, or came by it,

What stuff 'tis made of, whereof it is born,

I am to learn.

Where there is no certain cause there can be no certain cure, and Spike Milligan is a case in point. For 40 years, he has been in and out of psychiatric institutions, and has been treated with tranquillisers, anti-depressants, hypnotherapy, and electro-convulsive therapy. He is now on lithium. It is too early to say whether its effects will be lasting, but Dr Clare is keeping his fingers crossed. So am I.