The lack of relief through the simple: let the medicine be compounded for when universal relief for the disease is not found in the lone simple it is necessary to compound dissimilar contrary medicines, and to make one medicine from them, as is obvious from the wounds for which a healing medicine and a flesh-growing medicine are required to be compounded, such as the medicine compounded from myrrh, incense, and the likes. So therefore, it is necessary for the rational physicians to make a composite medicine from the simples. It suffices for us what we have said about the simples.
Before we speak of the composite medicines it is necessary first of all to speak of the estimated quantity of the simples which are to be put into the composite medicines, for Constantinus says, ‘Since the medicine varies in its qualities, in its efficacy, and in its virtues it is necessary to include a little of some medicines, much of others and of still others a medium quantity.’