note), conceives it, the human body is affected in a mode, which involves the nature of the said external body; thus so long as the mind conceives things, which increase or help the power of activity in our body, the body is affected in modes which increase or help its power of activity (III.Post.

i.); consequently (III.

xi.) the mind's power of thinking is for that period increased or helped.

Thus (III.vi., ix.) the mind, as far as it can, endeavours to imagine such things.

Q.E.D.
PROP.XIII.