"It is possible that mankind is on the threshold of a golden age; but, if so, it will be necessary to kill off nine-tenths of the present population."

"Free thought has always been a perquisite of aristocracy."

"The most fundamental of all moral duties is to exercise our intelligence to the utmost."

"I say quite deliberately that the Christian religion, as organized in its churches, has been and still is the principal enemy of moral progress in the world."

"We civilised men do our utmost to check the process of elimination; we build asylums for the imbecile, the maimed, and the sick .... Thus the weak members of civilised societies propagate their kind. …"