Thus did Dante know the whole round of science in his time better than any modern university man. People who take exception to his knowledge fail to realize its environment. They may smile a little scornfully now at his complacent acceptance of the Ptolemaic system without a question, but it must not be forgotten that for three centuries after his time educated men still continued to accept it, and that even the distinguished Jesuit astronomer, Clavius, to whom we owe the Gregorian reformation of the calendar and the restoration of the year to its proper place as regards the heavens, not only accepted it, but worked out his calendar reform problems by means of it. Clavius’s great contemporary, Tycho-Brahe, the distinguished Danish astronomer, found no reason to reject it. Even Lord Bacon, who with perverted historical sense is still proclaimed the father of modern experimental science, also accepted the Ptolemaic system, and found that it thoroughly explained all the phenomena of the heavens, while he rejected the Copernican system, then nearly a century before the world, because he thought it did not. The surprise, however, is not in Dante’s knowledge of astronomy, but in his familiarity with details of biology that enables him to reason, though in poetic language, with straightforward and logical directness with regard to basic thought in this science that is usually considered so thoroughly modern.
Another surprising feature is the knowledge of the habits of birds and of insects. Our modern students of nature are supposed to be the first who went deeply enough into these subjects to make them material for literature. Here, however, is Dante describing, in a few picturesque words, characteristic peculiarities of birds and insects, which our modern writers spend pages over, yet tell us scarcely more about them. A little knowledge of Dante is evidently the best antidote that our generation can have for that foolish persuasion that the Middle Ages were ignorant of science and that the universities taught nothing but nonsense about nature.
James J. Walsh, The Popes and Science (1908)