P10: The being of substance does not pertain to the essence of man, or substance does not constitute the form of man.

Dem.: For the being of substance involves necessary existence (by IP7). Therefore, if the being of substance pertained to the essence of man, then substance being given, man would necessarily be given (by D2), and consequently man would exist necessarily, which (by A1) is absurd, q.e.d.

Schol.: This proposition is also demonstrated from IP5, viz. that there are not two substances of the same nature. Since a number of men can exist,22 what constitutes the form of man is not the being of substance. Further, this proposition is evident from the other properties of substance, viz. that substance is, by its nature, infinite, immutable, indivisible, etc., as anyone can easily see.

Cor.: From this it follows that the essence of man is constituted by certain modifications of God/Nature’s attributes.

Dem.: For the being of substance does not pertain to the essence of man (by P10). Therefore, it is something (by IP15) which is in God/Nature, and which can neither be nor be conceived without God/Nature, or (by IP25 C) an affection, or mode, which expresses God/Nature’s nature in a certain and determinate way.

Schol.: Everyone, of course, must concede that nothing can either be or be conceived without God/Nature. For all confess that God/Nature is the only cause of all things, both of their essence and of their existence. I.e., God/Nature is not only the cause of the coming to be of things, as they say, but also of their being.

But in the meantime many say that anything without which a thing can neither be nor be conceived pertains to the nature of the thing.24 And so they believe either that the nature of God/Nature pertains to the essence of created things, or that created things can be or be conceived without God/Nature—or what is more certain, they are not sufficiently consistent. The cause of this, I believe, was that they did not observe the {proper} order of Philosophizing. For they believed that the divine/universal nature, which they should have contemplated before all else (because it is prior both in knowledge and in nature) is last in the order of knowledge, and that the things that are called objects of the senses are prior to all. That is why, when they contemplated natural things, they thought of nothing less than they did of the divine/universal nature; and when afterwards they directed their minds to contemplating the divine/universal nature, they could think of nothing less than of their first fictions, on which they had built the knowledge of natural things, because these could not assist knowledge of the divine/universal nature. So it is no wonder that they have generally contradicted themselves. But I pass over this. For my intent here was only to give a reason why I did not say that anything without which a thing can neither be nor be conceived pertains to its nature—viz. because singular things can neither be nor be conceived without God/Nature, and nevertheless, God/Nature does not pertain to their essence. But I have said that what necessarily constitutes the essence of a thing is that which, if it is given, the thing is posited, and if it is taken away, the thing is taken away, i.e., the essence is what the thing can neither be nor be conceived without, and vice versa, what can neither be nor be conceived without the thing.