NICHOLAS PRÆPOSITUS, about 1140, was the president of the school, and wrote a famous book called the _Antidotarium_—a Pharmacopœia as we should call it. This book of recipes was compiled from the works of the Arabian doctors Mesues, Avicenna, Actuarius, Nicolaus Myrepsus, as well as from Galen. It is interesting as giving the forms which the compounders of the prescriptions were sworn on their oath to observe; they promised to make up all their potions, syrups, etc., “_secundum prædictam formam_,” and they further promised that their drugs should be fresh and sufficient. It shows also that there was a habit of writing a prescription when a patient was visited; this, it seems, was a custom which originated with the Arabian physicians.[765] Nicholas was also the author, says Dr. Baas,[766] of a work called “_Quid pro Quo_,” which was a list of drugs which were equivalent to other drugs, and might be used as substitutes for each other in case of either running short. Dr. Baas says our expression “Quid pro Quo” originated from this. The writings of Bartholomæus and of Copho the Younger (between 1100 and 1120), says Daremberg, are of great interest in the history of medicine; they show how great was the freedom of spirit which existed at Salerno at this time. Copho described certain diseases which were not referred to in the works of other writers of Salerno; for example, ulceration of the palate and trachea, polypi, scrofulous tumours of the throat, condylomata, etc. Bartholomæus and Copho also held certain original ideas as to the classification of fevers. Copho distinguished between medicine for the rich and for the poor: the rich are delicate, and must be cured agreeably; the poor wish only to be cured at as little cost as possible. Thus the nobles must be purged with finely powdered rhubarb, the poor, with a decoction of mirobalanum, sweetened or not. Naturally the more precious drugs would be used for the wealthy, and probably the poor, who could not afford the complicated and terrible confections of mediæval pharmacy, might have congratulated themselves on being treated with a few simples instead of the precious messes which the wealthy had to swallow. JOHANNES PLATEARIUS deserves notice as having been the inventor of the term “Cataracta,” in place of the ancient Egyptian “ascent” and the Greek “hypochosis,” in classical Latin “suffusio humorum” (Hirsch).[767] MATTHÆUS PLATEARIUS was the son of the above; he composed a _Practica Brevis_ and other books on medicine; it is not certain at what precise date they flourished. ÆGIDIUS “CORBOLENSIS,” canon of Paris, physician to Philip Augustus, king of France (1165-1213), wrote a poem on the decline of Salerno as a medical school; he describes the doctors as caring nothing for books which were not full of recipes, and the professors as merely beardless boys. The famous but somewhat mysterious “Four Masters” were commentators on the surgery of Roger and Roland.