اخلاق, بخش III, قضیه 6

Individual things are modes whereby the attributes of God are expressed in a given determinate manner (I. xxv. Coroll.); that is, (I. xxxiv.), they are things which express in a given determinate manner the power of God, whereby God is and 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.