But however great the value we allow to the observations of the priests, it is to the Ionian Greeks that we owe the definite foundation of science in the proper sense; it was they who gave the raw material the needed accuracy and generality of application, A comparison of the societies in the nearer East to which we have referred, with the history of China affords the strongest presumption of this. In the later millenniums B.C. the Chinese were in many points ahead of the Babylonians and Egyptians. They had made earlier predictions of eclipses and more accurate observations of the distance of the sun from the zenith at various places. They had, too, seen the advantages of a decimal system both in weights and measures and in the calculations of time. But no Greek genius came to build the house with the bricks that they had fashioned, and in spite of the achievements of the Chinese they remained until our own day the type in the world of a settled and contented, although unprogressive, conservatism. Science then among its other qualities contains a force of social movement, and our age of rapid transformation has begun to do fuller justice to the work of the Greeks, the greatest source of intellectual life and change in the world. We are now fully conscious of the defects in their methods, the guesses which pass for observations, the metaphysical notions which often take the place of experimental results.[80] But having witnessed the latest strides in the unification of science on mathematical lines, we are more and more inclined to prize the geometry and astronomy of the Greeks, who gave us the first constructions on which the modern mechanical theories of the universe are based. We shall quote from them here only sufficient illustrations to explain and justify this statement. The first shall be what is called Euclidean geometry, but which is in the main the work of the Pythagorean school of thinkers and social reformers who flourished from the seventh to the fifth centuries B.C. This formed the greater part of the geometrical truth known to mankind until Descartes and the mathematicians recommenced the work in the seventeenth century. The second greatest contribution of the Greeks was the statics and the conics of which Archimedes was the chief creator in the third century B.C. In his work he gave the first sketch of an infinitesimal calculus and in his own way performed an integration. The third invaluable construction was the trigonometry by which Hipparchus for the first time made a scientific astronomy possible. The fourth, the optics of Ptolemy based on much true observation and containing an approximation to the general law.