If a single cell, under appropriate conditions, becomes a man in the space of a few years, there can surely be no difficulty in understanding how, under appropriate conditions, a cell may, in the course of untold millions of years, give origin to the human race.

Those whose hardships are set forth in pamphlets and proclaimed in sermons and speeches which echo throughout society, are assumed to be all worthy souls, grievously wronged; and none of them are thought of as bearing the penalties of their misdeeds.

Any piece of knowledge which the pupil has himself acquired- any problem which he has himself solved, becomes, by virtue of the conquest, much more thoroughly his than it could else be. The preliminary activity of mind which his success implies, the concentration of thought necessary to it, and the excitement consequent on his triumph, conspire to register the facts in his memory in a way that no mere information heard from a teacher, or read in a schoolbook, can be registered.

Opinion is ultimately determined by the feelings, and not by the intellect.

During human progress, every science is evolved out of its corresponding art.

Agnostics are people who, like myself, confess themselves to be hopelessly ignorant concerning a variety of matters, about which metaphysicians and theologians, both orthodox and heterodox, dogmatize with the utmost confidence.

That feelings of love and hate make rational judgments impossible in public affairs, as in private affairs, we can clearly enough see in others, though not so clearly in ourselves.