Q.E.D.
Corollary .-- In so far as the human mind imagines an external body, it has not an adequate knowledge thereof.
Proof .-- When the human mind regards external bodies through the ideas of the modifications of its own body, we say that it imagines (see II.xvii.

note); now the mind can only imagine external bodies as actually existing.

Therefore (by II.

xxv.), in so far as the mind imagines external bodies, it has not an adequate knowledge of them.

Q.E.D.
PROP.XXVII.