It is open to man to increase the element of the divine in his nature, and to do so is the highest virtue.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“It does not appear that Aristotle believed in personal immortality, in the sense in which it was taught by Plato and afterwards by Christianity. He believed only that, in so far as men are rational, they partake of the divine, which is immortal. It is open to man to increase the element of the divine in his nature, and to do so is the highest virtue. But if he succeeded completely, he would have ceased to exist as a separate person. This is perhaps not the only possible interpretation of Aristotle’s words, but I think it is the most natural. CHAPTER XX Aristotle’s Ethics IN the corpus of Aristotle’s works, three treatises on ethics have a place, but two of these are now generally held to be by disciples.” source