P7: The striving by which each thing strives to persevere in its being is nothing but the actual essence of the thing.

Dem.: From the given essence of each thing some things necessarily follow (by IP36), and things are able {to produce} nothing but what follows necessarily from their determinate nature (by IP29). So the power of each thing, or the striving by which it (either alone or with others) does anything, or strives to do anything—i.e. (by P6), the power, or striving, by which it strives to persevere in its being, is nothing but the given, or actual, essence of the thing itself, q.e.d.