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.

Philosophy and Art both render the invisible visible by imagination.

All bad Literature rests upon imperfect insight, or upon imitation, which may be defined as seeing at second-hand.

Mathematicians do not write for the circulating library.

A man may be variously accomplished, and yet be a feeble poet.

Vehemence without feeling is but rant.

Every one who has seriously investigated a novel question, who has really interrogated Nature with a view to a distinct answer, will bear me out in saying that it requires intense and sustained effort of imagination.