Charles Darwin book The Descent of Man, and Selection in Relation to Sex
volume I, "Introduction", page 3 http://darwin-online.org.uk/content/frameset?pageseq=16&itemID=F937.1&viewtype=image <br class="br">Source: The Descent of Man (1871) <br class="br">Context: It has often and confidently been asserted, that man's origin can never be known: but ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.