The author of "On Ancient Medicine" launches immediately into a critique of opponents who posit a single "cause in all cases" of disease, "having laid down as a hypothesis for their account hot or cold or wet or dry or anything else they want". The method put forward in this treatise "could certainly be characterized as an empirical one", preferring the effects of diet as observed by the senses to cosmological speculations, and it was seized upon by Hellenistic Empiricist doctors for this reason. However, "unlike the Empiricists, the author does not claim that the doctor's knowledge is "limited" to what can be observed by the senses. On the contrary, he requires the doctor to have quite extensive knowledge of aspects of the human constitution that cannot be observed directly, such as the state of the patient's humors and internal organs".