The Enchiridion (Version 2) 13 : 1

If you would improve, submit to be considered without sense and foolish with respect to externals. Wish to be considered to know nothing: and if you shall seem to some to be a person of importance, distrust yourself. For you should know that it is not easy both to keep your will in a condition conformable to nature and (to secure) external things: but if a man is careful about the one, it is an absolute necessity that he will neglect the other.