So natural to mankind is intolerance ... that religious freedom has hardly anywhere been practically realized.

In this age, the mere example of non-conformity, the mere refusal to bend the knee to custom, is itself a service. Precisely because the tyranny of opinion is such as to make eccentricity a reproach, it is desirable, in order to break through that tyranny, that people should be eccentric.

When one's ideas are not challenged, one's ability to defend them weakens.

My father taught me that the question Who made me? cannot be answered, since it immediately suggests the further question, Who made God?

The validity of all the Inductive Methods depends on the assumption that every event, or the beginning of every phenomenon, must have some cause; some antecedent, upon the existence of which it is invariably and unconditionally consequent.

Photography is a brief complicity between foresight and luck.

My father never permitted anything which I learnt to degenerate into a mere exercise of memory. He strove to make the understanding not only go along with every step of the teaching but...precede it.