iption of ninety-five different kinds of precious stones, among
them the pearl, of seven metals, of salt, vitriol, alum, arsenic,
marcasite, nitre, tutia, and amber. Albert's {321} volumes on the
vegetables and plants were reproduced under the editorship of Meyer,
the historian of botany in Germany, and published in Berlin (1867).
All Albert's books are available in modern editions.

In a word, there was scarcely a subject in natural science which
Albert did not treat, in what would now be considered a formal serious
volume, and no department of science that he did not illuminate in
some way, not only by the collection of information that had
previously been in existence, but also by his own observations, and
especially by his interpretations of the significance of the various
phenomena that had been observed. His work is especially noteworthy
for its lack of dependence on authority and the straightforward way in
which the great pioneer of modern science made his observations.

Some of Albert's contemporaries, and especially his pupils, were
almost as distinguished as he was himself in the physical sciences.

In a previous chapter we spoke particularly of Roger Bacon's attitude
toward the physical sciences, above all in what concerns the
experimental method. He was typically modern in the standpoint that he
assumed, as the only one by which knowledge of the things of nature
can be obtained. It will be interesting now to see the number of
things which Friar Bacon succeeded in discovering by the application
of the principle of testing everything by personal observation, of not
accepting things on second-hand authorities, and of not being afraid
to say, "I do not know," in trying to learn for himself. His
discoveries will seem almost incredible to a modern student of science
and of education who has known nothing before of the progress of
science made {322} by this wonderful man, or who has known only
vaguely that Friar Bacon was a great original thinker in science, in
spite of the fact that his life-history is bounded by the thirteenth
century. I may say that the material of what I have to say of him, and
also of his great contemporaries, Albertus Magnus and St. Thomas
Aquinas, is taken almost literally from the chapter of my book, The
Thirteenth Greatest of Centuries, on What They Studied at the
Universities.

Roger Bacon has been declared to be the discoverer of gunpowder, but
this is a mistake, since it was kno