 Plato makes it clear that both of these processes, one preceding the other, must be part of one’s philosophical education. One of his deepest methodological convictions (affirmed in Meno, Theaetetus, and Sophist) is that in order to make intellectual progress we must recognize that knowledge cannot be acquired by passively receiving it from others: rather, we must work our way through problems and assess the merits of competing theories with an independent mind. Accordingly, some of his dialogues are primarily devices for breaking down the reader’s complacency, and that is why it is essential that they come to no positive conclusions; others are contributions to theory-construction, and are therefore best absorbed by those who have already passed through the first stage of philosophical development. We should not assume that Plato could have written the preparatory dialogues only at the earliest stage of his career. Although he may well have begun his writing career by taking up that sort of project, he may have continued writing these “negative” works at later stages, at the same time that he was composing his theory-constructing dialogues. For example although both Euthydemus and Charmides are widely assumed to be early dialogues, they might have been written around the same time as Symposium and Republic, which are generally assumed to be compositions of his middle period—or even later.