There is a curious moment in Locke's Some Thoughts Concerning Education (1693) when he turns to the question of what discourses on ethics a young English gentleman in the making should be encouraged to read. This is a question of some importance, one would have thought, in a treatise whose stated goal is an education to virtue and service to one's country, especially given Locke's claim that education “is that which makes the great difference in mankind.” “… of all the men we meet with,” he says, “nine parts of ten are what they are, good or evil, useful or not, by their education” (&1). But the brevity of his treatment here – earlier in the treatise he has spent at least ten times as long on proper methods of toilet training and five times as long on the question of whether children should be allowed to eat melons and plums or apples and pears – as well as the brevity of his actual reading list, occasion some surprise. Indeed, Locke explicitly recommends reading just two books in the sphere of morality:

Diogenes Laertius reports that Zeno was the first to introduce the word ‘kathēkon’ and to write a treatise on the topic. He also suggests that, in connection with these reflections on kathēkonta, Zeno reversed Hesiod's well-known tag about the value of following good advice relative to that of knowing things for ourselves. According to Zeno,

Although few things are so characteristic of the Stoics as their penchant for dispensing advice, Zeno's remark is initially rather puzzling. Surely, we might object, Hesiod is the one who has it right: merely following another's advice, whether in the form of specific individual instructions or more general rules, should hardly take precedence over knowing things for ourselves.

Zeno, however, apparently defended his own ranking by postulating a critical link between an ability to accept advice and action. A crucial prerequisite for praxis, he explained, is being capable of accepting and following the sound advice of others; by itself, knowing things on one's own holds no special guarantees with respect to one's actions. Yet, this added bit of explanation seems hardly less puzzling, especially given Zeno's overall endorsement of the Socratic claim that knowledge is sufficient for virtuous action.