Page:Popular Science Monthly Volume 80.djvu/360

350 of nature. Of August de Chateaubriand, who died July 4, 1848, he speaks as his "old friend, famous for his descriptive powers." Nor does he fail to speak of Arago in the most affectionate terms, quotations from whose letters fill many pages of notes, and for whose attainments he had profound respect.

Humboldt begins his work with a description of celestial phenomena and then comes down to the earth. He refers with respect to the labors of Hipparchus, Eratosthenes and Euclid, as of mathematicians of the first rank. He credits Aristarchus of Samos with having anticipated Copernicus in his theory of the universe. He recognizes the value of Strabo's geography, written after its author had entered his eighty-third year, and makes use of the works of the Plinys, the elder and the younger. To Hipparchus of Sicily, and Galen of Pergamos, physician and anatomist, he refers as men of the highest attainments. He praises the Arabs not only for their observations of the heavens and their careful mathematical calculations, but for their skill in chemistry and their experiments in order to discover its value in medicine. He says they were acquainted with many of the qualities and uses of sulphuric and nitric acid, and were aware of the fact that bodies can be decomposed and reunited. He is at pains to show how nearly related to each other most discoveries are, and that they are made in almost every instance by men who miss only by a little the discovery of some great truth which a little while after, other more fortunate men see. Preparations, Humboldt tells us, for the voyages of great sailors just before Columbus were made in the twelfth century. Three men in the thirteenth century, Roger Bacon, Albertus Magnus and Vincentius of Beauvais, would have been eminent in any century. As independent thinkers. Duns Scotus, William of Occam and Nicolas of Cusa led the thought of the world from the time of Ramus, Campanella and Bruno to Descartes. It was in 1250 that Vincentius wrote his "Secula Naturæ" for the use of St. Louis and his queen Margaret. This and other works of his were forerunners of of the "Margarita Philosophia" of Father Reisch, published in 1486, a book which Humboldt praises and of which he made some use and which he declares was instrumental in diffusing knowledge in the last half of the fifteenth century. Of the writings of Father Joseph Acosta, the Jesuit who published his "Natural History of the Indies" in 1590, it is enough to say that they prepared the way for works of Vossius, which Newton used, and in which Humboldt finds the groundwork of physical geography. Many events which were of importance in his day Humboldt traces back to the fifteenth and the beginning of the sixteenth centuries. These are the doubling of the Cape of Good Hope by Vasco di Gama, the discovery of America by Columbus, the voyages of Amerigo Vespucci and his son, and Magellan's circumnavigation of the globe. That same period witnessed a rare manifestation of intellectual power as well as the growth