The manuscript for this book was virtually complete only a few months before the death of Mary J. Gregor on October 31, 1994. She had finished not only nearly all of the texts themselves, but also the introductions and editorial notes accompanying the individual works. Only two short essays remained to be translated. Apart from minor revisions (to which she had agreed), the only other editorial work left to be done was the General Introduction and the glossaries. Some corrections in the translations were due to the helpful comments of B. Sharon Byrd, Thomas McCarthy, and Georg Geismann.

Gregor's translations of Kant are characterized not only by meticulous linguistic accuracy and scholarly erudition but also by an unfailing sense of style and an uncanny ability to render Kant's meaning into readable and even elegant English. Over a period of more than thirty years, she produced excellent English versions of Kant's writings: The Doctrine of Virtue (1964), Anthropology from a Pragmatic Standpoint (1974), The Conflict of the Faculties (1979), “On the Philosopher's Medicine of the Body” (1985), and the whole of the Metaphysics of Morals (1991). Her translations of all these works are being used as the basis of the Cambridge Edition versions.

In addition to her accomplishments as a translator, Gregor made significant contributions to Kant scholarship. She wrote articles on Kant's moral and political philosophy, and her book Laws of Freedom (1963) was almost alone at the time in stressing the indispensability of the Metaphysics of Morals for a proper understanding of Kant's ethical theory.