Tradition
St. Gregory Nazianzen
Orations
Oration 2 › Section 13
13. This then is the first point in what we have said, which it is right for us to guard against, viz.: being found to be bad painters of the charms of virtue, and still more, if not, perhaps, models for poor painters, poor models for the people, or barely escaping the proverb, that we undertake to heal others while ourselves are full of sores.
Source: Orations (New Advent)