Aristotle divides the physical world between a celestial realm, which is alive but neither hot nor cold, and a sublunary realm, which is moved by heat in two forms: the vital heat of the biological works and the inanimate fire, the operation of which is explained in the Meteorologica. In the context of the second division we find Aristotle distinguishing between the macrocosm (roughly the world according to Physics, de Caelo, Generation and Corruption and the Meteorologica) and the microcosm (the realm of the biological works, the individual sublunary animals). Wilson argues that this second division does not overturn the first one, but rather complements it, for it has some bearing on the question of solar and vital heat. He further argues that Aristotle mediates the macrocosm and the microcosm through the conceptual apparatus of the spontaneous generation in which heat plays a manifest role.