So far as he was concerned in the development of Greek philosophy proper, he was inferior to some of his disciples, Yet he gave a turning-point to a new period when he awakened the _idea_ of knowledge, and was the founder of the method of scientific inquiry, since he pointed out the legitimate bounds of inquiry, and was thus the precursor of Bacon and Pascal. He did not attempt to make physics explain metaphysics, nor metaphysics the phenomena of the natural world; and he reasoned only from what was generally assumed to be true and invariable. He was a great pioneer of philosophy, since he resorted to inductive methods of proof, and gave general definiteness to ideas. Although he employed induction, it was his aim to withdraw the mind from the contemplation of Nature, and to fix it on its own phenomena,--to look inward rather than outward; a method carried out admirably by his pupil Plato. The previous philosophers had given their attention to external nature; Socrates gave up speculations about material phenomena, and directed his inquiries solely to the nature of knowledge. And as he considered knowledge to be identical with virtue, he speculated on ethical questions mainly, and the method which he taught was that by which alone man could become better and wiser. To know one's self,--in other words, that "the proper study of mankind is man,"--he proclaimed with Thales. Cicero said of him, "Socrates brought down philosophy from the heavens to the earth." He did not disdain the subjects which chiefly interested the Sophists,--astronomy, rhetoric, physics,--but he chiefly discussed moral questions, such as, What is piety? What is the just and the unjust? What is temperance? What is courage? What is the character fit for a citizen?--and other ethical points, involving practical human relationships.