 Quite apart from the question whether Spinoza intended to impose this more active reading of inertial dynamics on Cartesian philosophy, either deliberately or unawares, he clearly made the striving conatus of individual modes an important centerpiece of the mature philosophy he presented in the Ethics. IIIp6, which articulates the conatus doctrine according to which “each thing, as far as it can by its own power, strives to persevere in its own being”, has been the subject of a great amount of interpretive puzzlement in the literature. A main focus of this puzzlement is the extent to which IIIp6 represents a teleological element in Spinoza's natural philosophy. It is certainly central to Spinoza's subsequent treatment of human psychology, according to which we strive to obtain those things that increase our power and to avoid those that diminish it. Spinoza takes his conatus principle to license inferences from sentences of the form “x would increase A‘s power” to sentences of the form “A does x so far as A is able”; this is genuine explanatory teleology, treating a state to be achieved—the increase of power—as an end towards which a thing's activity is directed, and thus as an explanatory ground for behaviors.