Those who have learned precepts as mere theory want to vomit them up immediately, just as people with weak stomachs do with their food. Digest your precepts first, and you will not vomit them up in this way; otherwise they really do turn to vomit, tainted matter unfit to eat. Then show us some change that results from those precepts in your own ruling faculty, just as athletes can show their shoulders as the results of their training and diet, or those who have learned various arts can show the result of their learning.

A builder does not come up and say, “Listen to me lecturing on the builder’s art”, but acquires a contract to build a house and shows by building it that he knows the art. And you should do likewise; eat as a man, drink as a man, adorn yourself, marry, sire children, play your part as a citizen; put up with abuse, bear with an inconsiderate brother, bear with a father, bear with a son, neighbour, fellow-traveller.

Show us these things so we can see that you have in truth learnt something from the philosophers. No; but “Come and listen to me reading out my commentaries.” Away with you! Look for someone else to vomit over.

- Epictetus, The Discourses