tion. They were Albertus Magnus, the teacher of the other two, Thomas Aquinas and Roger Bacon. All three of them were together at the University of Paris shortly after the middle of the thirteenth century. Any one who wants to know anything about the attitude of mind of the medieval universities, their professors and students and of all the intellectual world of the time towards science and observation and experiment, should read the books of these men. Any other mode of getting at any knowledge of the real significance of the science of this time is mere pretense. These constitute the documents behind any scientific history of the development of science at this time.
It is extremely interesting to see the attitude of these men with regard to authority. In Albert's tenth book (of his "Summa") in which he catalogues and describes all the trees, plants and herbs known in his time he observes: "All that is here set down is the result of our own experience, or has been borrowed from authors whom we know to have written what their personal experience has confirmed; for in these matters experience alone can be of certainty." In his impressive Latin phrase "experimentum solum certificat in talibus." With regard to the study of nature in general he was quite as emphatic. He was a theologian as well as a scientist, yet in his treatise on "The Heavens and The Earth" he declared that "in studying nature we have not to inquire how God the Creator may, as He freely wills, use His creatures to work miracles and thereby show forth His power. We have rather to inquire what nature with its immanent causes can naturally bring to pass."
Just as striking quotations on this subject might be made from Roger Bacon. Indeed, Bacon was quite impatient with the scholars around him who talked over much, did not observe enough, depended to excess on authority and in general did as mediocre scholars always do, made much fuss on second-hand information—plus some filmy speculations of their own. Friar Bacon, however, had one great pupil whose work he thoroughly appreciated because it exhibited the opposite qualities. This was Petrus—we have come to know him as Peregrinus—whose observations on magnetism have excited so much attention in recent years with the republications of his epistle on the subject. It is really a monograph on magnetism written in the thirteenth century. Roger Bacon's opinion of it and of its author furnishes us the best possible index of his attitude of mind towards observation and experiment in science.
- "De cœlo et mundo," 1, tr, iv., x.