orders. Aristotle considered the problem further, without arriving at a completely satisfactory solution, and his well-trained successor, Demetrius, after ten years of practical experience in governing Athens, took the consciousness of it with him to Egypt. Were not constraints necessary on the guardians also ? It is reported that Demetrius had a hand in setting up a royal code for Ptolemy the son of Lagus. No one will suppose that the laws of Egypt were written and promulgated all at once, once for all. What we have of Ptolemaic laws shows that these were constantly being retouched and augmented. Nevertheless, Demetrius came to Egypt in a formative period when it was seeking both men and ideas, and it would be strange if he had not been put to work. Qui custodiet ipsos custodes ? The guardians, the members of the bureaucracy who were intended to make the h.ws effective and see that