'One long sin against mankind'

"If a man, holding a belief which he was taught in childhood or persuaded of afterwards, keeps down and pushes away any doubts which arise about it in his mind, purposely avoids the reading of books and the company of men that call into question or discuss it, and regards as impious those questions which cannot be easily asked without disturbing it--the life of that man is one long sin against mankind."

— William Clifford (19th cent. British mathematician)