In sum, all actions and habits are to be esteemed good or evil by their causes and usefulness in reference to the commonwealth, and not by their mediocrity, nor by their being commended. For several men praise several customs, and, contrarily, what one calls vice, another calls virtue, as their present affections lead them.
Thomas HobbesThe Imagination that is raised in man (or any other creature imbued with the faculty of imagining) by words, or other voluntary signs, is that we generally call Understanding; and is common to Man and Beasts.
Thomas HobbesThere is no such thing as perpetual tranquillity of mind while we live here; because life itself is but motion, and can never be without desire, nor without fear, no more than without sense.
Thomas Hobbes