In his eighteenth year, Aristotle left Stagira and went to Athens, the centre of letters and learning in Greece—doubtless attracted thither by the fame of the philosopher, Plato. It appears, however, that during the three first years of his residence there, Plato was absent on a visit to Sicily. There can be no doubt that Aristotle paid particular attention to anatomy and medicine, as appears both from his circumstances in youth, and what we know of his best writings. It is also probable, as is indicated by some statements of ancient writers, that for a space he practised, like Locke, the healing art; he must, however, from an early age, have devoted his whole time to the study of philosophy and the investigation of nature, and have abandoned all thoughts of an exclusively professional career. His eagerness for the acquisition of knowledge, and his extraordinary acuteness and sagacity, doubtless attracted Plato’s attention at an early period; thus we are told that his master called him “the Intellect of the school,” and his house, the “House of the reader;” that he said Aristotle required the curb, while Zenocrates, a fellow-disciple, required the spur; some of which traditions are probably true. We are likewise informed that when reading he used to hold a brazen ball in his hand over a basin, in order that, if he fell asleep, he might be awaked by the noise which it would make in falling. Although Aristotle did not during Plato’s life, set up any school in opposition to him, as some writers have stated, he taught publicly in the art of rhetoric, and by this means became the rival of the celebrated Isocrates, whom he appears, notwithstanding his very advanced age, to have attacked with considerable violence, and to have treated with much contempt.