Aristotle (384–322 B.C.E.) curbed the strain of intellectual mysticism that had been inaugurated by Parmenides (c. 515–450 B.C.E.) and he formalized common sense inways that checked the speculative excesses of his teacher, Plato (c. 428–c. 348 B.C.E.). This enabled a solid foundation for empiricism, or knowledge based on sensory observation and direct experience. Aristotle accomplished his task via encyclopedic accounts of the existing knowledge of his day, assessments of that knowledge, and developments of it into new areas, using new methods of thought. He was a rare combination of a highly well-informed and diligent scholar and an original thinker. Like his nineteenth century successor Georg Wilhelm Friedrich Hegel (1770–1831), Aristotle was capable of “thinking the whole world.” But unlike Hegel, he thought of the whole world not as an abstract and speculative theorist would but as an ordinary person would, if he or she could do that.