"This perceiving, active being is what I call mind, spirit, soul, or myself. By which words I do not denote any one of my ideas, but a thing entirely distinct from them, wherein they exist, or, which is the same thing, whereby they are perceived; for the existence of an idea consists in being perceived."

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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.

— George Berkeley