Moral philosophy is often disappointing to those who, unaware of the nature of the subject, look there for insight into the human condition. One reason for this is that, ever since Aristotle rejected Socrates’ strange identification of knowledge and virtue, and insisted that the moral consists of doing rather than knowing (or, in the language of the profession, of practical rather than pure reason), astonishingly few philosophers have reconsidered the extent to which moral questions may be questions of understanding. But, without some such notion, morality will not have depth and nor, therefore, will the moral philosophy that purports to elucidate it.