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.

Mathematicians do not write for the circulating library.

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.

The real people of genius were resolute workers not idle dreamers.

Ideas are forces; our acceptance of one determines our reception of others.

A cell is regarded as the true biological atom.

It is not true that a man can believe or disbelieve what he will. But it is certain that an active desire to find any proposition true will unconsciously tend to that result by dismissing importunate suggestions which run counter to the belief, and welcoming those which favor it. The psychological law, that we only see what interests us, and only assimilate what is adapted to our condition, causes the mind to select its evidence.