This paper argues that the four elements exist in different ways in mixtures and homogenous parts of substances. According to Aristotle’s definition in De caelo, the elements exist in virtue of themselves in the compound bodies which they compose. However, if we assume that they exist in the same way in hylomorphic compounds as they exist in the compound bodies which they directly compose, a discrepancy arises between Aristotle’s definition of element and his hylomorphic theory, because the elements cannot exist (...) potentially, on the one hand, as the elements themselves, and, on the other hand, as the matter of a hylomorphic compound, at the same time. To solve this problem, homogenous bodies have been distinguished into mixtures and homogenous parts of hylomorphic individuals. According to Aristotle, it is only in mixtures that the elements exist in potentiality, while in the formation of the homogenous parts of a new substance generated from the mixtures, the elements which exist in the mixture are destroyed so that they can no longer exist in the hylomorphic compounds as themselves. (shrink)