There will be some fundamental assumptions which adherents of all the variant systems within the epoch unconsciously presuppose. Such assumptions appear so obvious that people do not know what they are assuming because no other way of putting things has ever occurred to them. With these assumptions a certain limited number of types of philosophic systems are possible, and this group of systems constitutes the philosophy of the epoch.

Every organism requires an environment of friends, partly to shield it from violent changes, and partly to supply it with its wants.

Mathematics, in its widest significance, is the development of all types of formal, necessary, deductive reasoning.

No Roman ever died in contemplation over a geometrical diagram.

The worth of men consists in their liability to persuasion. They can persuade and can be persuaded by the disclosure of alternatives, the better and the worse. Civilization is the maintenance of social order, by its own inherent persuasiveness as embodying the nobler alternative. The recourse to force, however, unavoidable, is a disclosure of the failure of civilization, either in the general society or in a remnant of individuals. Thus in a live civilization there is always an element of unrest.

I always feel that I have two duties to perform with a parting guest: one, to see that he doesn't forget anything that is his; the other, to see that he doesn't take anything that is mine.

Without adventure civilization is in full decay. ... The great fact [is] that in their day the great achievements of the past were the adventures of the past.