St. George William Joseph Stock, A Guide to Stoicism
“ Following out this conception the Stoics identified a life in accordance with nature with a life in accordance with the highest perfection to which man could attain. Now, as man was essentially a rational animal, his work as man lay in living the rational life. And the perfection of reason was virtue. Hence the ways of nature were no other than the ways of virtue. And so it came about that the Stoic formula might be expressed in a number of different ways which yet all amounted to the same thing. ”
