Greek philosopher (384-322 BCE). A pupil of Plato, the tutor of Alexander the Great, and the author of works on logic, metaphysics, ethics, natural sciences, politics, and poetics, he profoundly influenced Western thought. In his philosophical system, which led him to criticize what he saw as Plato's metaphysical excesses, theory follows empirical observation and logic, based on the syllogism, is the essential method of rational inquiry. An ancient city- state whose remains are located outside of Mexico City. First began in the first century, when the inhabitants of the village located on the site began to plan and build a huge city. At its peak in the 700s, had between 150,000 and 200,000 people living there, making it one of the largest cities in existence at the time. Had more than 20 pyramids consecrated to the gods, but the largest was the Pyramid of the Sun. It became the center of a thriving trade network that extended far into Central America. There is no evidence that it conquered its neighbors or tried to create an empire, however, evidence of the art styles and religious beliefs from the city have been found throughout Mesoamerica. After centuries of growth, the city began a sudden and abrupt decline, which is believed to have been caused by an invasion from outside forces or a fight among the city's nobility. It was abandoned by 750.