Philosophy and Art both render the invisible visible by imagination.

Science is the systematic classification of experience.

There are many justifications of silence; there can be none of insincerity.

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

A man may be buoyed up by the efflation of his wild desires to brave any imaginable peril; but he cannot calmly see one he loves braving the same peril; simply because he cannot feel within turn that which prompts another. He sees the danger, and feels not the power that is to overcome it.

A cell is regarded as the true biological atom.

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.