The frequent grouping of the doctors with the teachers in the Theodosian Code suggests that the public State-paid physicians taught as well as practised their art. Reinach[516] warns against certainty on this point, but it is at least probable. The wording of Constantine’s law[517] of September 27, 333, confirms the supposition. Doctors and teachers are proclaimed exempt from military service and public burdens so that they may have leisure to train others in their art—‘quo facilius studiis liberalibus et memoratis artibus multos instituant’. Of the original five classes of _archiatri_ paid by the State—those of the court, those belonging to the municipalities, the heads of the medicine guilds, those in charge of the public gymnasia, and those who attended the Vestals—it was probably the second, the municipal doctors, who were the teachers of their profession. If this is so, it proves that Rome was not the only place where doctors could be trained, as Denk seems to think.[518] Indeed, the provinces were more interested in medicine than Rome herself. Pliny[519] said in a broad and general way that for six hundred years Rome had got on without doctors, and it is well known that the Roman doctors made no important contribution to the science. Egyptians, Greeks, Gauls—these were the physicians of Rome. Pliny writes to Trajan asking him to give the citizenship to a doctor from whom he had derived benefit: ‘est enim peregrinae condicionis, manumissus a peregrina’.[520] The doctor who attends Hadrian on his death-bed is a foreigner.[521] Ammianus describes the growing fame of the Alexandrian school of medicine during the fourth century, as such, that a man, even if his actual work turned out badly, need only say that he had been trained at Alexandria in order to gain commendation.[522] Then, as now, it was a lucrative profession, according to the proverb ‘Galenus dat opes’;[523] nor did the benefit to the sick always correspond to the doctor’s gain.[524] A word may perhaps be added on the _agrimensores_, who represent the department of science among the Romans that was most scientifically employed, though all their mathematics came from Hiero of Alexandria.[525] Their work was partly military (the marking out of camps and locating of positions for the army) and partly civil (the surveying of colonies and provinces for revenue purposes). In cases of ‘controversia de loco’, the Theodosian Code appoints them judges.[526] At first they were free to practise where and when they could, but in our period they were attached to guilds, and stood under a ‘primicerius mensorum’.[527] This organization of the ‘agrimensores’ implies a certain amount of training and a professional test of proficiency.[528]