Human existence is girt round with mystery: the narrow region of our experience is a small island in the midst of a boundless sea. To add to the mystery, the domain of our earthly existence is not only an island of infinite space, but also in infinite time. The past and the future are alike shrouded from us: we neither know the origin of anything which is, nor its final destination.

A person should be free to do as he likes in his own concerns; but he ought not to be free to do as he likes in acting for another, under the pretext that the affairs of the other are his own affairs.

It appears, then, to be a condition of a genuinely scientific hypothesis, that it be not destined always to remain an hypothesis, but be certain to be either proved or disproved by.. .comparison with observed facts.

The principles which men profess on any controverted subject are usually a very incomplete exponent of the opinions they really hold.

Every great movement must experience three stages: ridicule, discussion, adoption.

The philosophy of reasoning, to be complete, ought to comprise the theory of bad as well as of good reasoning.

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