John of St. Amand, to whose similar conditions for medical experimentation we just alluded, was a canon of Tournai who seems to have written a little later than Peter, since he describes the death from vomiting of a bishop of Tournai which took place in 1261.[1682] It is in his commentary on the Antidotarium of Nicolaus that John gives his seven conditions for medical experimentation. After having said that on account of the scarcity and incompleteness of experience, we should sometimes learn the virtues of simple medicines “through doctrine,” John for a page or two discusses other matters, but then reverts to the subject of experimentation. A medicinal simple, he says, may be known by two methods, “the way of experience and the way of reason.” “And because the principles of experience are better known to us than the principles of reason, let us first inquire concerning the knowledge of medicinal simples by the way of experience.” He goes on to say that experience is twofold as it is supported or not supported by reason. If unsupported by reason experience or experiment is timorous and fallacious. As for experience supported by reason, it should conform to these seven requirements.[1683] First, “the medicinal simple which is being tested should be pure and free from every extraneous quality, lest by such extraneous quality the proper operation of the medicine be impeded, and in consequence experimental knowledge.”[1684] Here the use of the adjective, “experimental” is interesting. Second, the experimentation should be with a simple and not a complicated disease.[1685] Third, the simple should be tested in two contrary types of disease, because sometimes a medicine cures one disease by its “complexion” or elemental properties and another by its occult virtue. Thus scammony cures both quotidian and tertian fever; the first because scammony is of a hot nature; but the second by its occult virtue and not because scammony is of a cold nature, for it is not.[1686] Fourth, the virtue of the medicine should correspond to the quality of the patient. Fifth, essence and accident should not be confused; water, for example, may be heated, but is not of a hot nature.[1687] Sixth, the experiment should be often repeated. For if a medicine is tested in the cases of five men and has a heating effect upon them all, still that is not adequate proof that it will always have a heating effect, for they may have all been of a cold or temperate constitution, whereas a man of hot nature would not be heated by the simple in question. Seventh, the test should be on the human body and in varying states of health. Trying the medicine upon a lion may not prove anything as to its effect upon a man.[1688] John seems to have taken his conditions directly from Galen rather than from Petrus Hispanus, since only three of them are identical with Peter’s, whereas all but one occur in his own Concordances from Galen’s works.[1689] John of St. Amand repeats the experiment with the hazel rod which we have already encountered in William of Auvergne. According to John the two split halves tend to reunite because it is natural for them to be together, but he adds that some old women make use of it with utterance of a useless incantation as a matrimonial charm, asserting that if the halves unite, the marriage will be a happy one.[1690]
Natural and occult science in John of St. Amand.
It was not my intention to speak of John of St. Amand further than to compare his remarks on experimental method with those of Petrus Hispanus, but the Histoire Littéraire has already presented some specimens of his views, which it will be worth repeating to show that his experimental tendency has the same accompaniment of mingled credulity and scepticism and of occult science and signs of magic as we have noted in other cases. Thus he rejects the story that the beaver castrates itself to escape the pursuit of hunters on the ground that the animal has not that much sense, but believes that beavers enslave one another. From the fact that herons are subject to diarrhoea he argues that men with long necks and legs should not resort to purgatives, and he states that pearls comfort the heart by similarity, since they are hard like the heart. He enters into long and obscure explanations how it is that application of the flesh of a snake extracts the venom from its bite, and “is not exempt from astrological ideas.”[1691] But the writings of John of St. Amand have carried us well along into the second half of the thirteenth century; in the next chapter we must turn back to a man whose literary activity began in the Erst half of that century, Albertus Magnus.
[1614] Ptolemaei Lucensis Historia Ecclesiastica. Liber XXIII, cap. xxi, in Muratori, XI, 1176. For the life of John XXI see also HL XIX (1838) 322-34; J. T. Koehler, Vollständige Nachricht von Pabst Johann XXI, Göttingen, 1760; L. Zdekauer, in Bullettino Senese di Storia Patria, VI (1898-1899); Richard Stapper, Papst Johannes XXI, Münster, 1898, in Kirchengesch. Studien herausg. v. Dr. Knöpfler, Band IV, Heft iv.
[1615] Millot-Carpentier (1901). G. Porro, in his catalogue of Trivulzian MSS at Milan, Turin, 1884, calls Peter “Petrus Julianus Ulissiponensis.”
[1616] Royal 13-A-VII, 15th century, fol. 149r.
[1617] Stapper (1898), p. 4, “In illis namque laribus ab annis teneris diutius observati variis scientiis inibi studiose vacavimus et per annos plurimos....”
[1618] See too, C. von Prantl, Michael Psellus und Petrus Hispanus, 1867.
[1619] HL XIX, 330.
[1620] Harleian 5218, fols. 1r-3r, Epistola Magistri Petri Hyspani missa ad Imperatorem Fridericum super regimen sanitatis. It seems strange, however, that Peter should call himself, as he does in this work, “senex artis medicinae professor,” before 1250, when he would have been rather less than forty years of age. Other MSS. are: CLM 615, 13-14th century, fols. 41-68; BN 7446, 15th century.