This, with its penetrating astronomy and its ever-amazing inwardness, was, I venture to guess, evolved at that time and by creative personalities of the Isaiah stature from relics of the old Babylonian religion.[326] About 1000, the Chaldeans were a group of Aramaic-speaking tribes like the Israelites, and lived in the south of Sinear--the mother tongue of Jesus is still sometimes called Chaldean. In Seleucid times the name was applied to a widespread religious community, and especially to its priests. The Chaldean religion was an astral religion, which before Hammurabi the Babylonian was _not_. It is the deepest of all interpretations of the Magian universe, the World-Cavern[327] and Kismet working therein, and consequently it remained the fundamental of Islamic and Jewish speculation to their very latest phases. It was by it, and not by the Babylonian Culture, that after the seventh century there was formed an astronomy worthy to be called an exact science--that is, a priestly technique of observation of marvellous acuteness.[328] It replaced the Babylonian moon-week by the planet-week. Ishtar, the most popular figure of the old religion, the goddess of life and fruitfulness, now became a planet, and Tammuz, the ever-dying and ever-revived god of vegetation, a fixed star. Finally, the henotheistic feeling announced itself; for Nebuchadnezzar the Great Marduk[329] was the one true god, the god of mercy, and Nebo, the old god of Borsippa, was his son and envoy to mankind. For a century (625-539) Chaldean kings were world-rulers, but they were also the heralds of the new religion. When temples were being built, they themselves carried bricks. The accession-prayer of Nebuchadnezzar, the contemporary of Jeremiah, to Marduk is still extant, and in depth and purity it is in nowise surpassed by the finest passages of Israelite prophecy. The Chaldean penitential psalms, closely related in rhythm and inner structure to those of the Jews, know the sin of which man is unconscious and the suffering that contrite avowal before the incensed god can avert. It is the same trust in the mercy of the Deity that finds a truly Christian expression in the inscriptions of the Bel temple of Palmyra.[330]