St. Thomas is not only the king of theologians, but the prince of moralists, and it has seemed a pity that his own words on matters of daily practice should have been so long inaccessible to the English reader. Technical Latin is not attractive to those who are unversed in it, and the student of ethics might be easily bewildered by the large admixture of speculative theology in the Summa. In this translation the separation of ethics from theology has been carried out in the main, and the English has been made as simple as the subject-matter permits. This is volume one out of two and a a translation of the principal portions of the second part of the Summa Theologica including more than three hundred endnotes.