Only a small percentage of Epicurus' writings have survived, partly because his philosophy became unpopular once the Hellenistic reaction to the classical tradition gave way to the resurgence of non-sceptical forms of Platonism and the subsequent rise of Christianity. Epicurus was interested in the practical problem of living well, and his discussion of evil is part of his solution to this problem. He rejected the dominant line of thought from the classical tradition of Plato and Aristotle and moved away from rationalism and towards empiricism. Epicurus thought that theoretical investigations are useful to correct the unfortunate and all too common tendency of human beings to form certain distressing but false beliefs. In contrast, Epicurus stresses memory in a way which suggests that he is part of the empiricist tradition that Plato and Aristotle rejected. In the Letter to Herodotus, Epicurus makes memory play an important role with respect to happiness and the good life.