'Generally speaking,' he once wrote, 'the errors in religion are dangerous; those in philosophy only ridiculous.' In the Dialogues, one of his supreme masterpieces, he savages most of the traditional arguments for the existence of God, shows how religion is often founded on ignorance and irrational fears and suggest that only 'the rational and philosphical kind' of religion (if any) can possibly stand up to serious scrutiny. Hume's intense scepticim and astounding ability to take nothing on trust led John Stuart Mill to call him 'the profoundest negative thinker on record,' yet this book is equally distinguished by the dramatic ebb and flow of argument put into the mouths of its characters. The result is one of the classic works on the nature of religion; it also makes crystal-clear the reason why A.J. Ayer called Hume the greatest of British philosphers.