It is right, perhaps, to observe in this place, that Dr. Smith, in his Dictionary of Biography, speaks of the 'History of Animals' as partly the result of the royal liberality of Alexander; and doubtless Aristotle would gladly have introduced into his work any fresh materials which might have been made available to him either during his residence at the Macedonian court, or by the subsequent victories of Alexander in the East, if the information so obtained had reached Athens in sufficient time to be incorporated. But in the first instance he would naturally use the materials ready to his hand in the works of his predecessors, and these were not few. The animals also which he describes are principally those of Greece and of the countries with which the enterprising Greeks had frequent and commercial intercourse. He says little of the animals of the interior of Asia and of India, and speaks very cautiously of such as he does mention; and one who quotes his authorities so freely would hardly have failed to notice the sources of his information. The study, or at least the knowledge of the classification of animals appears to have been carefully pursued in the earliest period of man's history. The oldest records that we possess contain abundant notices of the peculiarities of animals. The Mosaic law abounds in them, in its distinctions between the clean and the unclean, a distinction not then first established, but of the most remote antiquity. Indeed it could hardly be otherwise than that men engaged in the pursuits of agriculture and the chase should study the habits of the animals that were valuable to them, as well as those which were injurious. A study thus commenced by necessity, would eventually be pursued for its own sake; and not a few would be found who would investigate, and, as far as they could, record the various phenomena they observed. The paintings of Egypt and the sculptures of Assyria are our witnesses of the skill with which animals and plants were drawn, and of the minute perception of their external forms; and the knowledge thus gained in the ancient centres of civilization would be sure to circulate and increase when the intercourse with foreign nations spread the knowledge and philosophy so acquired.