47 Besides, we are aware that it is better to offer our own reins to others more skilful than ourselves, than, while inexperienced, to guide the course of others, and rather to give a kindly hearing than stir an untrained tongue; and after a discussion of these points with advisers who are, I fancy, of no mean worth, and, at any rate, wish us well, we preferred to learn those canons of speech and action which we did not know, rather than undertake to teach them in our ignorance. For it is delightful to have the reasoning of the aged come to one even until the depth of old age, able, as it is, to aid a soul new to piety. Accordingly, to undertake the training of others before being sufficiently trained oneself, and to learn, as men say, the potter's art on a wine-jar, that is, to practise ourselves in piety at the expense of others' souls seems to me to be excessive folly or excessive rashness— folly, if we are not even aware of our own ignorance; rashness, if in spite of this knowledge we venture on the task.
Source: Orations (New Advent)