A prodigious stimulus was thus given to learning, and it has left its impress upon the world's civilization. Here Euclid wrote the theorems which are still studied by the college students of to day. Here Archimedes studied mathematics under Conon. Here Eratosthones made astronomy a science. Here Ptolemy wrote his "Syntaxes." Here Ctesibius and Hero invented the steam engine. Here true philosophy flourished, and for the first time, too, in the world's history. The people of the Orient had dabbled in speculative thought before this, but the results achieved showed that the Oriental mind is not adapted to abstract reasoning. The luxurious habits and voluptuous surroundings and tropical climate of the Orient tend more toward poetry, music and love and languor than toward psychical contemplations. The awe-awakening phenomena of nature, which confront the Oriental everywhere, naturally lead him to accept as _a priori_ principles what the philosophers of the Occident make the subject of endless, and for the most part, incomprehensible and unsatisfactory systems of philosophy. It is for this reason that the great religions of the world sprang from Oriental soil, while the great philosophical systems took roots in Western lands. Yet, up to this period, not even the West, with all its labors, had sounded the depths of true philosophy. The entire pre-Socratic philosophy wasted its energies upon the futile effort to find some principle for the explanation of nature, which to the Hebrew mind had been solved thousands of years before in the opening verse of the Bible. One thought it to be _water_; another, _air_; and a third an original _chaotic matter_. The Pythagoreans declared that _number_ is the essence of all things, and the Eleatics believed they were nearer the truth by negating all division in space and time. The Atomists endowed each atom with gravity and motion, and accounted thus for the origin of all physical existences and states. Socrates and Plato both came much nearer to the solution of the problem; the former postulated self-knowledge as the starting point of all philosophy, and the latter combined all preceding systems into one scheme, with an _infinitely wise and just and powerful spirit_ as its guiding principle, but idealistically only. The additional realistic view of things had not yet been reached, and could not be reached, for that depends upon universal and exact and scientific knowledge, which prior to the great age of Alexandrian learning, to which all ages and climes and nations contributed their experiences and observation and knowledge, had never yet existed. Aristotle, the teacher of Alexander, and the friend of Ptolemy, thus found through Alexandrian influence, opportunities for philosophical reasoning, which necessarily gave his system an almost inestimable advantage over his predecessors. From the study of particulars he rose to a knowledge of universals, advancing to them by induction.