It must not be thought, however, that Dante's interest in science was exhausted by his excursions into astronomy. This has already been more than hinted at in some of the passages quoted, which show his interest in other phases of science. In the modern time, however, it is almost the rule, that if a scholar who is not a scientist, and especially if he happens to be, as Dante was, a literary man, indulges in some scientific pursuits, he has at most but an interest in one branch of science. Quite as often as not he rather prides himself on knowing nothing at all about this department of knowledge. Specialism has invaded even scientific education, and a man specializes in some favorite department of science for his avocation, and is apt to know very little about other departments. Dante was not thus constituted, however. It will be comparatively easy to show that every form of scientific thought interested him, and that his love of nature led him into nature study, in the {355} best sense of that very modern term, and caused him to make observations for himself, or so retain the observations of others that he had heard or read, that he was able to use them very forcibly and appropriately in the figurative language of his great poem. Alexander von Humboldt, the distinguished German naturalist and leader of scientific thought in the early nineteenth century, whose compliment to Albertus Magnus, quoted in the chapter on Science at the Medieval Universities, is probably a surprise to most people, but serves to show how wide was the reading of this great scientist, was also an attentive student of Dante, and has a passage with regard to the Florentine poet's knowledge of science quite as striking as that with regard to the great scholastic's excursions into the same field. In his Cosmos he has the following tribute to Dante as a student of nature and as a loving observer of natural phenomena: "When the story of the Arabic, Greek or Roman dominion--or, I might almost say, when the ancient world had passed away, we find in the great and inspired founder of a new era, Dante Alighieri, occasional manifestations of the deepest sensibility to the charms of the terrestrial life of nature, whenever he abstracts himself from the passionate and subjective control of that despondent mysticism which constituted the general circle of his ideas." With regard to the famous description of the river of light in the thirtieth canto of the Paradiso, Humboldt declared that the picture must have been suggested to Dante by the phosphorescence seen so beautifully and so luxuriantly in the Adriatic Sea at times. The passage itself is so beautiful and is so well worth the reading a {356} second time, even for those who have read it before, that I give it a place here, followed by Humboldt's comment.