V. (18) These are the causes which may be advanced by probable conjecture, to explain the question which is raised on this point; for the true causes God alone knows. But having said what is fitting concerning these matters, I shall now proceed in regular order to discuss the laws themselves with accuracy and precision: first of all of necessity, mentioning this point, that of his laws God himself, without having need of any one else, thought fit to promulgate some by himself alone, and some he promulgated by the agency of his prophet Moses, whom he selected, by reason of his pre-eminent excellence, out of all men, as the most suitable man to be the interpreter of his will. (19) Now those which he delivered in his own person by himself alone, are both laws in general, and also the heads of particular laws; and those which he promulgated by the agency of his prophet are all referred to those others; (20) and I will explain each kind as well as I can.