The study of the errors into which great minds have fallen in the pursuit of truth can never be uninstructive. … No man is so wise but that he may learn some wisdom from his past errors, either of thought or action, and no society has made such advances as to be capable of no improvement from the retrospect of its past folly and credulity.

Charles Mackay (1814-1889) Scottish poet, journalist, song writer

Extraordinary Popular Delusions and the Madness of Crowds (1841)