Pico della Mirandola at the close of the fifteenth century made a trenchant criticism of Peter’s erudition, when he characterized him as “a man fitted by nature to collect rather than to digest.” But this judgment was also too severe, for Peter was no mere compiler, but something of an experimental astronomer as well as a painstaking and critical translator, voluminous commentator upon Aristotle, and great medical authority. In the Conciliator he makes several references to his personal astronomical observations and to other treatises which he has composed upon astronomical topics and which are at least in part extant. He did not hesitate to correct the astronomical calculations of Ptolemy, and appreciated the margin of error in astronomical observations caused by variations in the construction of instruments as well as in their employment by the human observer.[2787] His Lucidator, we have seen, was intended to parallel in the field of astronomy and astrology the achievement of the Conciliator in that of medicine; but the portion completed or extant is not a great addition to Peter’s science, since it covers about the same ground already discussed in portions of the Conciliator and more especially in the treatise on the motion of the eighth sphere.

The Conciliator his masterpiece.

The Conciliator therefore remains his chief work and the one for which he is most famous, his masterpiece and most influential writing. Like the Opus Maius of Roger Bacon, it to a large extent covers his views as expressed elsewhere and is representative of his philosophy and learning as a whole. It is in many ways a valuable historical document, providing a good example of scholastic method, a broad picture of the state of medieval medicine, and much incidental illustration of the more general knowledge of Peter’s times, as when he alludes to the overland travelers and to the ocean voyages of the thirteenth century. He learned from Marco Polo that there was human life in the Antipodes, he cites a letter of John of Monte Corvino from India “in the coasts where lies the body of the Apostle Thomas,” he alludes to the attempt of two Genoese galleys to reach India by sea “almost thirty years ago”[2788]—two centuries before Vasco da Gama and Columbus. The Conciliator does not, however, quite cover the entire field of medieval science. The subjects of “geometry and perspective,” for instance, Peter rather avoids, explaining, “The arguments taken from the books of geometricians and students of perspective, such as Euclid, Alhazen, and others, and marked out by letters of the alphabet, I omit because most of those for whom I am writing are unfamiliar with that sort of thing.”[2789]

Its method.

The Conciliator is made up of over two hundred questions or “Differences” which Peter and his associates have been investigating publicly for the past ten years. Each problem is stated and any doubtful terminology is explained; the utterances of past authorities anent the question are reviewed; the true solution is then reached and the reasons for it given; fourth and finally, hostile objections are answered. This rigid scheme of argumentation does not, however, prevent Peter from indulging in a deal of rather rambling digression. This makes a very long volume, especially as supplementary questions or corollaries are added to some of the two hundred odd Differentiae. Also it is, like most works in scholastic form, hard and tiresome reading, as one has to keep in mind all the authorities and objections which Peter has cited and raised until he finally gets around to answering them. Many of the questions concern purely medical matters and admit little debate between philosophers and physicians. The first ten, however, deal with general questions such as whether medicine is a science, whether a doctor ought to be a logician, whether the human body is amenable to medicine, and whether the physician can help the sick by a knowledge of astronomy. Nearly a hundred distinctions are then concerned with medical theory concerning the elements, the physical constitution, generation, the members of the human body, fevers, and kindred questions. The last odd hundred distinctions deal with matters of medical practice and personal hygiene.

Specimens of its questions.

The mere list of these questions is interesting and illuminating, and a few of them may be reproduced here to show the kind of questions then debated by doctors—some of them are identical with the questions put by Petrus Hispanus in his Commentary on the Diets of Isaac—and to illustrate the broader scientific and philosophical interests of Peter’s volume and time.

11.Is the number of the elements four or otherwise?
14. Has air weight in its own sphere?
23. Is the brain of hot or moist complexion?
28. Is manhood hotter than childhood or youth?
30. Does blood alone nourish?
42. Is the flesh or the heart the organ of touch?[2790]
52. Does the marrow nourish the bones?
57. Is vital virtue something different from natural and animal virtue?
66. Is spring temperate?
67. Is life possible below the equator?
69. Is the white of an egg hot and the yolk cold?
70. (Supplement). Is wine good for children?
72. Is there a mean between health and sickness?
77. Is pain felt?
79. Is a small head a better sign than a large one?
80. Are the arteries dilated when the heart is and constricted also when it is?
81. Is there attraction exercised when the arteries dilate and a loosening when they are constricted?
83. Is musical consonance found in the pulse?
101. Can a worm be generated in the belly?
103. (Supplement). Is death more likely to occur by day or night?
110. (Supplement). Are eggs beneficial in fevers?
114. Does the air alter us more than food or drink does?
115. Is life shortened more in autumn than other seasons?
118. (Supplement). Should one take exercise before or after meals?
119. Should heavy food be taken before light?
120. Should one eat once, twice, or several times a day?
121. Should dinner be at noon or night?[2791]
122. Should one drink on top of fruit?
123. Should one sleep on the right or left side?
135. Does confidence of the patient in the doctor assist the cure?
153. Is every cure by contrary?
154. Should treatment begin with strong or weak medicine?
157. Does sleep help the cure?
171. Is cold water good in fevers?
182. (Supplement). Can fever coincide with apoplexy?
183. Is paralysis of the right side harder to cure than that of the left?
193. Can consumption be cured?
194. Does milk agree with consumptives?
204. Is a narcotic good for colic?
206. Is blood-letting from the left hand a proper treatment for gout in the right foot?

Was Peter the founder of Averroism at Padua?

Peter has often been called a disciple of Averroes and the founder of Averroism in Italy at Padua,[2792] but I have noticed little in his works to substantiate this. Renan admits that Peter knew neither the Colliget nor the medical works of Averroes, while the doctrine of religious change according to astrological conjunctions which he takes as a sign of Averroism[2793] in Peter came of course from much earlier Arabian astrologers. Indeed, it would seem that most of the points of view which are loosely designated by the word “Averroism” had been common enough among earlier Arabic writers and had even in considerable measure been taken from other sources than Averroes himself by the Latin world. Only if we accept the very dubious and loose assertion of Renan that “medicine, Arabism, Averroism, astrology, incredulity, became almost synonymous terms,”[2794] can we connect Peter of Abano with Averroism and even then we have the obstacles that Peter often makes profession of Christian faith and that Steinschneider asserts that he made no translations from the Arabic.[2795] And if astrological medicine be Averroistic, Peter was certainly not the first Averroist in Italy.