Metaphysical ghosts cannot be killed, because they cannot be touched; but they may be dispelled by dispelling the twilight in which shadows and solidities are easily confounded. The Vital Principle is an entity of this ghostly kind; and although the daylight has dissipated it, and positive Biology is no longer vexed with its visitations, it nevertheless reappears in another shape in the shadowy region of mystery which surrounds biological and all other questions.

Heart and Brain are the two lords of life. In the metaphors of ordinary speech and in the stricter language of science, we use these terms to indicate two central powers, from which all motives radiate, to which all influences converge.

If you feel yourself to be above the mass, speak so as to raise the mass to the height of your argument.

In its happiest efforts, translation is but approximation, and its efforts are not often happy. A translation may be good as translation, but it cannot be an adequate reproduction of the original.

Originality is independence, not rebellion; it is sincerity, not antagonism.

In complex trains of thought signs are indispensable.

Speak for yourself and from yourself, or be silent.