 In this light, the problem from the standpoint of the metaphysics of Extension — the basis of physical theory—is to explain why the specific configuration of a given existing mode makes any contribution at all to the determinations that result from the operation of external modal causes. It would be rash to read Ip28 in such a way that the causal powers of a body owe everything to the contributions of extrinsic causes, and nothing to the intrinsic nature of the body itself. Spinoza says in IIp13s A1 that “all modes by which a body is affected by another body follow both from the nature of the body affected and at the same time the nature of the affecting body, so that … different bodies may be moved differently by one and the same body.” (This is a key point in Spinoza's account of corporeal imagination, mental representation and the first kind of knowledge, offered at IIp17–41.) So the nature of an affected body makes a difference to the way it is affected extrinsically. This is not surprising. But then what explains why a body's nature makes a contribution to the way extrinsic influences determine it? As we saw in the previous sections, some answer to this question is required to make sense of the PLMM, and hence of all of the collision laws. The notion, shared by the teleological reading of conatus and the active reading of Spinozistic inertia, that it is in the nature of bodies actively to strive of their own power, would seem to help. But is it Spinozistic? At a minimum, any articulation of this notion must be free from illicit teleology.  Carriero (2017) suggests a non-teleological reading of the conatus doctrine that seems suitable.  On his view, conatus should be understood as an expression of the idea that it is constitutive of their finite individuality that individuals maximize their being.  “Dynamic constructions do tend to maximize their being.  But this is not because their reality is their end or good; it is an artifact of their stability as real individuals in the plenum” (152).  But what accounts for this stability?  We require a more probing examination into Spinoza's conception of the nature of individual bodies.