Wisdom and knowledge are, like a bad reputation, more easily won than lost
 Samuel Butler, The Note-Books of Samuel Butler (1912). copy citation

Context

“but when a thing is once well learnt it is even harder to unlearn it than it was to learn it. Would it be possible to unlearn the art of speech or the arts of reading and writing even if we wished to do so? Wisdom and knowledge are, like a bad reputation, more easily won than lost; we got on fairly well without knowing that the earth went round the sun; we thought the sun went round the earth until we found it made us uncomfortable to think so any longer, then we altered our opinion;” source