The first vague presentiment and rough sketch, as it were, of certain theories that have made a great noise in the world in our own day, may be traced, it is asserted, in the cosmogonic writings of ancient Chaldæa. Even the famous hypothesis of Darwin has been searched for and found, if we may believe the searchers. In any case it seems well established that the echo of these speculations reached the Ionian sages who were the fathers of Greek philosophy. Their traces are perceptible, some scholars declare, in the _Theogony_ of Hesiod. Possibly it is so; there are certainly some striking points of resemblance; but where the influence of such ideas is really and clearly evident is in those philosophic poems that succeeded each other about the sixth century B.C., all under the same title: _concerning nature_ (περὶφύσεως).[464] These poems are now lost, but judging from what we are told by men who read them in the original, the explanation they gave of the creation of the world and of the first appearance upon it of organized beings, differed only in its more abstract character from that proposed many centuries before, and under the form of a myth, by the priests of Chaldæa. If we may trust certain indications, these bold and ingenious doctrines crossed over from Ionia to the mainland of Greece, and reached the ears of such writers as Aristophanes and Plato. It does the greatest honour to Chaldæa that its bold speculations should have thus contributed to awaken the lofty intellectual ambitions and the scientific curiosity of Greece, and perhaps she may have rendered the latter country a still more signal service in teaching her those methods by whose use man draws himself clear of barbarism and starts on the road to civilization; a single example of this will be sufficient. It is more than forty years since Bœckh, and Brandis after him, proved that all the measures of length, weight and capacity used by the ancients, were correlated in the same fashion and belonged to one scale. Whether we turn to Persia, to Phœnicia or Palestine, to Athens or Rome, we are constantly met by the sexagesimal system of the Babylonians. The measurements of time and of the diurnal passage of the sun employed by all those peoples, were founded on the same divisions and borrowed from the same inventors. It is to the same people that we owe our week of seven days, which, though not at first adopted by the western nations, ended by imposing itself upon them.[465] As for astronomy, from a period far away in the darkness of the past it seems to have been a regular branch of learning in Chaldæa; the Greeks knew very little about it before the conquests of Alexander; it was more than a century after the capture of Babylon by the Macedonians that the famous astrological tables were first utilized by Hipparchus.[466]