P21: No one can desire to be blessed, to act well and to live well, unless at the same time he desires to be, to act, and to live, i.e., to actually exist.

Dem.: The Demonstration of this Proposition, or rather the thing itself, is evident through itself, and also from the definition of Desire. For the Desire (by Def. Aff. I) to live blessedly, or well, to act, etc., is the very essence of man, i.e. (by IIIP7), the striving by which each one strives to preserve his being. Therefore, no one can desire, etc., q.e.d.