The system of the Jehovist is quite a different one. According to him, Jahveh announces the Deluge to Noah only seven days beforehand. The waters are at their height for forty days, and decrease during forty more. After these eighty days Noah sends out the three birds at intervals of seven days, and thus it is on the 21st day after he has opened the window of the ark for the first time that he, too, goes out of the ark and offers his sacrifice to the Lord. Here the phases of the cataclysm are evidently calculated on those of the annual spring outflow of the Euphrates and Tigris, so that we need not hesitate to assign the origin of the very form of the tradition received by the Jehovist writer, to the cradle of the race of the Terahites in Chaldea. The overflow of the two rivers of Mesopotamia lasts, in fact, for an average of seventy-five days from the middle of March to the end of May; and twenty-six days later--that is, at the end of the 101 in all (80 + 21 = 75 + 26 = 101), when the Jehovist makes Noah leave the ark--the lands which have been inundated become once more practicable. What, moreover, in the Jehovist narrative bears a very marked impress of Chaldean origin is the part played in it by septennial periods; seven days intervening between the announcement and the beginning of the Deluge, seven between each sending forth of the birds. That religious and mystic importance attached to the heptade which gave rise to the conception of the seven days of creation, and to the invention of the week, is an essentially Chaldean idea. It is among the Chaldeo-Babylonians that we discover its origin and find its most numerous applications. The story of Khasisatra, in the poem of Uruk, invariably proceeds hebdomadally. The violence of the Deluge lasts seven days, and so does the stay of the vessel on Mount Nizir when the waters begin to go down. It is true, indeed, that the building of the vessel occupies eight instead of seven days; but we must add the time necessary for the embarkation of provisions, animals, passengers, and this will enable us to calculate the whole duration of Khasisatra's preparations between the vision sent him by Êa and the moment when he closes the vessel at the approach of the rain, as consisting of fourteen days or two hebdomades. This being granted, if the poem does not state precisely the intervals at which the three birds were sent forth, we are justified in applying here the figures used by the Jehovist in Genesis, and counting seven days between the first and second sending forth, seven between the second and third, and seven, lastly, between the departure of the bird which does not return, and the leaving the vessel. The whole interval, then, between the warning of Êa and the sacrifice of Khasisatra, amounts to seven hebdomades--plainly a number intentionally assigned. And the whole duration of the Deluge is doubled by the sacred writer, who was the author of the Jehovist document, 7 × 2 × 7, instead