The human faculties of perception, judgment, discriminative feeling, mental activity, and even moral preference, are exercised only in making a choice. He who does anything because it is the custom, makes no choice.

Everyone who receives the protection of society owes a return for the benefit.

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.

That a thing is peculiar; is no argument for its being blamable; since the most criminal actions are to a being like man not more unnatural than most of the virtues.

We have hitherto considered only two possibilities: that the received opinion may be false, and some other opinion, consequently, true; or that, the received opinion being true, a conflict with the opposite error is essential to a clear apprehension and deep feeling of its truth. But there is a commoner case than either of these; when the conflicting doctrines, instead of being one true and the other false, share the truth between them.

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.

It is given to no human being to stereotype a set of truths, and walk safely by their guidance with his mind's eye closed.