But to return to the Papal Physicians in our original meaning of the term. Alderotti's successor as physician to the Papal Court was scarcely, if any, less distinguished. This was Simon Januensis, the medical attendant to Pope Nicholas IV., whose pontificate lasted from 1288-1292. Simon did much to make the use of opium more scientific than it had been, and he established definite rules for its administration. Before this the anodyne effects of the drug had been well known, but the difficulty had been to regulate its dosage properly and prevent the use of too large quantities, while at the same time securing the administration of sufficient of the drug to relieve pain. At the beginning there was much prejudice with regard to opium. Indeed, as every physician knows, this prejudice has not entirely died out even in our own day. How much of good, then, Simon was able to accomplish because the prestige of his position as {209} Papal Physician helped to break down this prejudice, and how much human suffering he saved as a consequence, it is easy to understand. Simon is best known in the history of medical science as the author of what was probably the first important dictionary of medicine. This was called the Synonyma Medicinae or Clavis Sanationis, the Key of Health. Steinschneider has declared this book to be one of the most important works in the field of Synonymies. Julius Pagel, in his chapter on Therapeutics in the Middle Ages, in Puschmann's Handbook of the History of Medicine, already quoted, says that this Papal Physician succeeded in solving very happily the problem which he set himself, of gathering together the information that had been collected during past centuries with regard to medical words, and especially those relating to the use of various remedial measures. The industry of the writer may be very well appreciated from the fact that his glossary contains some six thousand articles. Its place in the history of science, as given by Meyer, the German historian of botany, is that for the understanding of the older words in natural science, no better aid than this can be found. He considers it the best work of its kind until Caspar Bauhin's similar volume came to replace it, but that was not until well on in the seventeenth century. Simon was greatly encouraged in this work by Popes Nicholas IV. and Boniface VIII., to both of whom he was body physician and at the same time an intimate friend.