Or, as we put it, in a sense they have and in a sense they have not; eg perhaps the elements of perceptible bodies are, as form, the hot, and in another sense the cold, which is the privation; and, as matter, that which directly and of itself is potentially these; and both these are substances and also the things composed of these, of which these are the principles (i.e. any unity which is produced out of the hot and the cold, eg flesh or bone); for the product must be different from the elements.