Therefore upon the learning of the lessons appropriate to each and every excellence, practical training must follow invariably, if indeed from the lessons we have learned we hope to derive any benefit. And moreover such practical exercise is the more important for the student of philosophy than for the student of medicine or any similar art, the more philosophy claims to be a greater and more difficult discipline than any other study. The reason for this is that men who enter the other professions have not had their souls corrupted beforehand and have not learned the opposite of what they are going to be taught, but the ones who start out to study philosophy have been born and reared in an environment filled with corruption and evil, and therefore turn to virtue in such a state that they need a longer and more thorough training.