The influence upon Greco-Roman civilization of certain legal terms like those covering the notions of "justice," "injustice" and "law" has been enormous. Yet the systematic study of those terms is a comparatively late phenomenon. We find it in the later dialogues of Plato and in Aristotle and his school. Aristotle's pupil and successor at the Lyceum, Theophrastus, was the author of a formal treatise De Legibus. In classical times generally there was a whole series of tracts class="EmphasisTypeItalic ">peri nomou, mostly, however, lost to us.¹ But if the systematic study of legal concepts had to wait until the fourth century b.c., the concepts had been there and were known and discussed by the Greeks long before.