This book has been made for a service which no one of its predecessors could be persuaded to render. It embodies the lectures its author has given to his classes in Ethics, and is, what it purports to be, distinctively a text-book. It touches existing controversies only so far as is necessary for the elucidation or defence of its own positions. The aim has been to condense rather than to expand its discussions, and to diminish rather than to multiply its pages. - Preface.