To be able to think freely, a man must be certain that no consequence will follow whatever he writes.

The liberty of the individual is a necessary postulate of human progress.

All the great things of humanity have been accomplished in the name of absolute principles.

The man who obeys is nearly always better than the man who commands.

None of the miracles with which ancient histories are filled, occurred under scientific conditions. Observation never once contradicted, teaches us that miracles occur only in periods and countries in which they are believed in and before persons disposed to believe in them.

Human cruelty took the form of a pact with the deity. A solemn oath was made to kill everything, in which people forbade themselves any display of reason or compassion. A city or a land was devoted to destruction and it was believed an insult to God if one did not observe the abominable oath.

The simplest schoolboy is now familiar with truths for which Archimedes would have sacrificed his life.