But appearances deceive. “Lust” is the third book in a series on the seven “deadly sins” which began life as a course by seven lecturers at the New York Public Library, that well-known den of vice. In the course of investigating lust, Mr Blackburn is lured irresistibly to the conclusion that there is nothing at all wrong with it. With the caveat that the word is often cheatingly used in such a way as to make lust wicked merely by definition (the Oxford English Dictionary calls it a “degrading animal passion”), it is hard not to be seduced by Mr Blackburn's sweet reasonableness.
So what is lust? Mr Blackburn starts by stripping it naked. After seven pages of analysis by counter-example and refinement, he defines it as an enthusiastic desire, which infuses the body, for sexual activity and its pleasures for their own sake. The subsequent tour of attitudes to this desire in western thought and literature is engagingly illustrated and masterfully argued, especially when it takes on the view that sex ought to be reserved for reproduction and not enjoyed for its own sake—an easy target, as Mr Blackburn demonstrates, but still a necessary one.
The author is no libertine, though. He does not go nearly as far as Epicurus and his populariser, Lucretius, who held that lust is superior to love. The Epicureans feared love as a kind of madness that overcomes the rational soul—in the fourth book of his “De Rerum Natura”, Lucretius gives a marvellously dyspeptic account of romance that is convincing if you have just fallen out of love but unpersuasive if you are falling in. Indulging in plenty of sex for its own sake, the Epicureans argued, is an effective remedy for the insanity of love. (This rationalisation for promiscuity is curiously little-used by the sex industry.)
Mr Blackburn's own sympathies lie with the account of lust given by Hobbes. The discussion is subtle, but to cut to the chase—as lust is wont to do—the essence of Hobbes's view is that the pleasure of lust is not only sensual but also a “delight of the mind”, because it consists of “two appetites together, to please, and to be pleased”. As Mr Blackburn puts it, lust involves a “pure mutuality”, a “joint symphony of pleasure and response”. Alas, it will probably take more than a slim volume of sweet reason to win over lust's enemies. Guilt about sex seems to run too deep for that.