2. The _Pythagoreans_ attempted a higher solution of this problem. The proportions and dimensions of matter rather than its sensible concretions, seemed to them to furnish the true explanation of being. They, accordingly, adopted as the principle of their philosophy, that which would express a determination of proportions, _i. e._ numbers. “Number is the essence of all things,” was their position. Number is the mean between the immediate sensuous intuition and the pure thought. Number and measure have, to be sure, nothing to do with matter only in so far as it possesses extension, and is capable of division in space and time, but yet we should have no numbers or measures if there were no matter, or nothing which could meet the intuitions of our sense. This elevation above matter, which is at the same time a cleaving to matter, constitutes the essence and the character of Pythagoreanism. 3. Next come the _Eleatics_, who step absolutely beyond that which is given in experience, and make a complete abstraction of every thing material. This abstraction, this negation of all division in space and time, they take as their principle, and call it pure being. Instead of the sensuous principle of the Ionics, or the symbolic principle of the Pythagoreans, the Eleatics, therefore, adopt an intelligible principle. 4. Herewith closes the analytic, the first course in the development of Grecian philosophy, to make way for the second, or synthetic course. The Eleatics had sacrificed to their principle of pure being, the existence of the world and every finite existence. But the denial of nature and the world could not be maintained. The reality of both forced itself upon the attention, and even the Eleatics had affirmed it, though in guarded and hypothetical terms. But from their abstract being there was no passage back to the sensuous and concrete; their principle ought to have explained the being of events, but it did not. To find a principle for the explanation of these, a principle which would account for the becoming, the event was still the problem. _Heraclitus_ solved it, by asserting that, inasmuch as being has no more reality than not being, therefore the unity of the two, or in other words the becoming, is the absolute principle. He held that it belonged to the very essence of finite being that it be conceived in a continual flow, in an endless stream. “Every thing flows.” We have here the conception of original energy, instead of the Ionic original matter; the first attempt to explain being and its motion from a principle analytically attained. From the time of Heraclitus, this inquiry after the cause of the becoming, remained the chief interest and the moving spring of philosophical development.