Hi.

I respond to the question, presenting my view.

Spinoza, 11.
That which states the terms[constitutes] of existance for the human mind, is basically nothing else than the _idea_ of an actually existing individual. [The idea refers - in my opinion - to the socratic cave theory, if you understand my meaning]

Spinoza, 13.
The object of the idea[reflection], stating the rules for the human mind, is the human body[which is the true form/reflectee].

Hope you will see my meaning.

Jani