  The human affects, for Spinoza, are a part of nature insofar as each can be redescribed in terms of striving, a property which all particular things in nature share. Desire and its varieties are striving itself, under a certain description. Human passions are for Spinoza changes, that is, increases or decreases, in the power with which we, or parts of us, strive. Active affects are all increases in the power with which we strive.