P20: There is also in God/Nature an idea, or knowledge, of the human Mind, which follows in God/Nature in the same way and is related to God/Nature in the same way as the idea, or knowledge, of the human Body.

Dem.: Thought is an attribute of God/Nature (by P1), and so (by P3) there must necessarily be in God/Nature an idea both of {NS: thought} and of all of its affections, and consequently (by P11), of the human Mind also. Next, this idea, or knowledge, of the Mind does not follow in God/Nature insofar as he is infinite, but insofar as he is affected by another idea of a singular thing (by P9).

But the order and connection of ideas is the same as the order and connection of causes (by P7). Therefore, this idea, or knowledge, of the Mind follows in God/Nature and is related to God/Nature in the same way as the idea, or knowledge, of the Body, q.e.d.