rk of most interest to us is the De Natura Rerum, a single
large volume in twenty books. It required some fifteen years of work,
and for some fifteen years before he began his work on it Thomas had
been writing various historical and biographical works. Thomas's
encyclopedic volume contains one book with regard to anatomy, one with
regard to human monsters, and books with regard to quadrupeds, birds,
marine monsters, fishes, serpents, worms, ordinary trees, aromatic and
medicinal plants and the virtues of herbs, and of curative waters of
various kinds. Then there are books on precious stones and their
cutting, on the seven regions and the humors of the air, on the earth
and the seven planets, and on the four elements and the Heavens and
eclipses of the sun and moon. When such a work was published for
general reading, it is easy to understand that no phase of information
with regard to nature failed to be of interest to readers of the
thirteenth century. Much that is absurd is contained in the book. But
when we compare it with books written in the early part of the
eighteenth century, we are apt to wonder rather at how little advance
had taken place in the four centuries of interval, than at the
ignorance of the medieval writer.

[Footnote 42: Studien zur Geschichte der Anatomie im Mittelalter von
Robert Ritter von Toeply, Leipzig und Wien. Franz Deuticke, 1898.]

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We have been able, of course, in this limited space to give only a
modicum of the evidence for the cultivation of the Physical Sciences
at the Medieval Universities, and their records in monumental works
still extant; but this will probably be enough to enable those who are
interested in the subject to realize its significance and to gather
further material if they so wish. The universities were ecclesiastical
institutions. Most of them derived their authority to give degrees
directly from the Popes. Appeals were frequently made to the Popes
with regard to the discipline and the teaching at the universities.
Most of the great teachers of physical science were ecclesiastics.
Nearly all the students were clerics. Many of those who were most
successful in science reached high preferment in the Church. Evidently
the pursuit of science did not prejudice their advancement, either in
their orders, when they belonged to any of the various religious
orders, or in the Church itself. They were the near and dear friends
of archbishops, cardinals and Popes. This i