acts; now no thing contains in itself anything whereby it can be destroyed, or which can take away its existence (III. iv.); but contrariwise it is opposed to all that could take away its existence (III. v.). Therefore, in so far as it can, and in so far as it is in itself, it endeavours to persist in its own being. Q.E.D.
PROP. VII. The endeavour, wherewith everything endeavours to persist in its own being, is nothing else but the actual essence of the thing in question.
Proof.—From the given essence of any thing certain consequences necessarily follow (I. xxxvi.), nor have things any power save such as necessarily follows from their nature as determined (I. xxix.); wherefore the power of any given thing, or the endeavour whereby, either alone or with other things, it acts, or endeavours to act, that is (III. vi.), the power or endeavour, wherewith it endeavours to persist in its own being, is nothing else but the given or actual essence of