There is no permanent absolute unchangeable truth; what we should pursue is the most convenient arrangement of our ideas.

He that complies against his will, Is of his own opinion still.

In practice it is seldom very hard to do one's duty when one knows what it is, but it is sometimes extremely difficult to find this out.

Business should be like religion and science; it should know neither love nor hate.

You cannot have a thing "matter" by itself which shall have no motion in it, nor yet a thing "motion" by itself which shall exist apart from matter; you must have both or neither. You can have matter moving much, or little, and in all conceivable ways; but you cannot have matter without any motion more than you can have motion without any matter that is moving.

All animals, except man, know that the principal business of life is to enjoy it - and they do enjoy it as much as man and other circumstances will allow.

Whereas, to borrow an illustration from mathematics, life was formerly an equation of, say, 100 unknown quantities, it is now one of 99 only, inasmuch as memory and heredity have been shown to be one and the same thing.