When a thing lies still, unless somewhat else stir it, it will lie still forever, is a truth that no man doubts of. But that when a thing is in motion, it will eternally be in motion, unless somewhat else stay it, though the reason be the same, namely, that nothing can change itself, is not so easily assented to.

Leviathan, Or, The Matter, Form, and Power of a Commonwealth, Ecclesiastical and Civil (2nd edition), Chapter II (p. 16)