Originally published in 1921, updated in 1932 and re-issued in 1966 with an introduction by Stephan Koerner, this book remains a classic introduction to the study of ethics. It clearly explains both the Aristotelian and the Kantian approach to ethical problems, by combining the advantages of a historical and systematic introduction. Much of the book is devoted to Aristotle and Kant, whose moral theories are important and who are influential forces in contemporary moral philosophy.