From: The Golden Sayings of Epictetus (translated by Hastings Crossley) - from Project Gutenberg.
The dress is suited to the craft; the craftsman takes his name from the craft, not from the dress. For this reason Euphrates was right in saying, "I long endeavoured to conceal my following the philosophic life; and this profited me much. In the first place, I knew that what I did aright, I did not for the sake of lookers-on, but for my own. I ate aright-unto myself; I kept the even tenor of my walk, my glance composed and serene-all unto myself and unto God. Then as I fought alone, I was alone in peril. If I did anything amiss or shameful, the cause of Philosophy was not in me endangered; nor did I wrong the multitude by transgressing as a professed philosopher. Wherefore those that knew not my purpose marvelled how it came about, that whilst all my life and conversation was passed with philosophers without exception, I was yet none myself. And what harm that the philosopher should be known by his acts, instead of mere outward signs and symbols?"