 Here, then, More fully accepts the precepts of the mechanical philosophy, but he refuses to accept that Cartesianism can account for all phenomena. As in his letters to Descartes, for example, he points out that the mechanical vortex theory should result in cylindrical heavenly bodies, so it must be the action of the Spirit of Nature that makes them spherical (see, for example, More 1662, in Antidote Against Atheism, separately paginated, 39; see also the Preface General, xv). He also points to magnetism and gravity as phenomena which are not convincingly explained by Descartes, as well as condensation and rarefaction. He also points to the Achilles heel of the mechanical philosophy, the generation and development of plants and animals, as well as the instinctive behaviour of animals. Later on in his career, however, More’s concern to establish the existence of immaterial spirit beyond all doubt, leads him to deny that bodies are capable even of mechanical interactions: “there is no Phaenomenon of Nature purely Mechanicall” (More 1668, 31). All phenomena, he says, are “not carried according to Mechanicall Necessity, but that there is a Principle that has a Prospection for the best, that rules all” (More 1686, 34).