But of all his measures, the one most admired was his distribution of the people into groups according to their trades or arts. For the city was supposed to consist of two tribes, as has been said, although it had no consistency, but was rather divided into two tribes, and utterly refused to become united, or to blot out its diversities and differences. On the contrary, it was filled with ceaseless collisions and contentions between its component parts. Numa, therefore, aware that hard substances which will not readily mingle may be crushed and pulverized, and then more easily mix and mingle with each other-owing to the smallness of their particles, determined to divide the entire body of the people into a greater number of divisions, and so, by merging it in other distinctions, to obliterate the original and great distinction, which would be lost among the lesser ones. He distributed them, accordingly, by arts and trades, into musicians, goldsmiths, carpenters, dyers, leatherworkers, curriers, braziers, and potters. The remaining trades he grouped together, and made one body out of all who belonged to them. He also appointed social gatherings and public assemblies and rites of worship befitting each body. And thus, at last, he banished from the city the practice of speaking and thinking of some citizens as Sabines, and of others as Romans; or of some as subjects of Tatius, and others of Romulus, so that his division resulted in a harmonious blending of them all together. Praise is also given to that measure of his whereby the law permitting fathers to sell their sons was amended. He made an exception of married sons, provided they had married with the consent and approval of their fathers. For he thought it a hard thing that a woman who had married a man whom she thought free, should find herself living with a slave.