Herbert Lionel Adolphus, professor of jurisprudence at Oxford University (1952–1968), was the most important and influential philosopher of law of the twentieth century. Bringing to bear the linguistic approach to philosophy championed by Wittgenstein and Hart's Oxford colleague, J. L. Austin, Hart transformed jurisprudence into the vibrant discipline it had been at the time of Jeremy Bentham and his student, John Austin. He revealed the law to be a fertile ground for addressing age-old philosophical questions on a wide range of topics, for example, the analysis of causation, human action and intention, responsibility and rights, and the very nature of morality. Ronald Dworkin, who succeeded Hart in the Oxford Chair, nicely expressed this feature of his predecessor's work in a speech delivered at Hart's memorial service: "Herbert showed how philosophy can be tutor to law, how lawyers' questions about punishment and...