As the soldiers of Alexander of Macedon brought home the jungle-fowl of India, and domesticated it in Europe; so the agents of Providence, acting in the realms of science, gathered up and transmitted just such elements as their successors would most need. As soon as mineral acids could be obtained, chemistry first began, a powerful means of decomposing matter; therewith the distillation of sea-water, described by Alexander of Aphrodisias in the time of Caracalla, became an invention of great importance. The new solvent was variously applied, and the scientific mind gradually became acquainted with the compound nature of matter, its chemical constituents, and their mutual affinities. Anatomical knowledge also improved under Roman teachers. Marinus, and Rufus of Ephesus, dissected monkeys, and distinguished between the nerves of motion and the nerves of sense. Ælian of Præneste wrote a history of animals, and Oppianus of Cilicia, a poem upon fishes. These contained some accurate descriptions, but few facts founded upon their own examination, or worthy of a standard work on natural history. Great numbers of elephants, elks, ostriches, crocodiles, panthers, tigers, and lions, were slaughtered in the Roman amphitheatre during four centuries, but without any result save that of a brutal enjoyment. In that great metropolis there was no academy of science, and no general interest in a high range of intellectual pursuits. Antonius Castor, the Roman physician, was the only citizen who is reported to have had a botanical garden, probably made to imitate those of Theophrastus and Mithridates, but of no more practical use to science than was the collection of fossil bones made by the emperor Augustus, in the museum of natural curiosities. Galen, the only anatomist of true scientific method, flourished under the Antonines, and died about A.D. 203. He was originally from Pergamus, but went early to Alexandria, where he perfected his professional skill, and then removed to Rome, the scene of his great trials and triumphs. His superiority excited the jealous hatred of the metropolitan physicians; but the reputation he had earned was superior to their malice. Galen regarded his chief publication as "a religious hymn in honor of the Creator." The noble undertaking of a "Description of the World," by Caius Plinius the Second, was doubtless the greatest contribution to general science made during the Augustan age. It comprised thirty-seven books, and was the first great Encyclopedia of Nature and Art. In all antiquity nothing had ever been attempted in like manner, and for many centuries it remained perfectly unique. In its dedication to Titus, the author appropriately applied to his work a Greek expression which signifies the abstract and compendium of universal knowledge and science.