E2P17C=====
The mind is able to regard as present external bodies, by which the
human body has once been affected, even though they be no longer in
existence or present.
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======= E2: PROP. 16, Corollary 2:
...the ideas, which we have of external bodies, indicate rather the constitution of our own body than the nature of
external bodies.

perception of externals is a decision of the mind to imagine a difference in the idea and the idea of itself.