  Locke and Newton accept similar ontologies. Although both (quite independently of one another) are characteristically circumspect about the nature of mind, they may be considered substance dualists. Newton, though indicating in the early manuscript De Gravitatione that he does not pretend to know the substantial foundation of minds, consistently presents God and minds as immaterial, lacking certain characteristics of body, namely, hardness, impenetrability and resistance. Similarly, Locke, though he explicitly allows the possibility of thinking matter in his Essay and discusses it at length with Stillingfleet, emphasizes that in all probability, the soul is immaterial (E IV.iii.6, pp. 540–541). But while Newton takes even immaterial spirits to be spatially extended, such that a mind can co-occupy place with a body and God with all bodies, it is not clear that Locke agrees. Agreement might be claimed on the basis of the several passages in the Essay. At E II xxvii.2 (p. 329 ), he locates spirits spatially: “Finite spirits having had each its determinate time and place of beginning to exist, the relation to that time and place will always determine to each of them its identity, as long as it exists.” And as the passage continues, he seems to echo Newton’s suggestion that substances of different kinds might share place; although substances of the same kind exclude one another out of the same place, he writes, “these three sorts of substances, as we term them, do not exclude one another out of the same place”. Yet a Cartesian interpretation does not seem impossible here, especially in light of remarks elsewhere; in discussing the possibility of thinking matter, the immaterial soul against which he contrasts it is  unextended.[25]