Nothing can be plainer, than that the motions, changes, decays, and dissolutions, which we hourly see befall natural bodies (and which is what we mean by the course of nature), cannot possibly affect an active, simple, uncompounded substance: such a being therefore is indissoluble by the force of nature, that is to say, the soul of man is naturally immortal.

A treatise concerning the principles of human knowledge (ed. 1734)