Darkness, silence, rest, the nightingale's song, the stars, the rising of the moon--these are all the material of this wonderful passage. Yet did ever such beauty fall with night upon such peace, save in Paradise alone? Once he had got his story, based on his few authorities, with hints unconsciously taken and touches added, perhaps, from his reading of other poets--of Caedmon, Andreini, and Vondel, of Spenser, Sylvester, Crashaw, and the Fletchers--Milton's first task was to reduce it to the strict relations of time and space. His blindness probably helped him by relieving him from the hourly solicitations of the visible world, and giving him a dark and vacant space in which to rear his geometric fabric. Against this background the figures of his characters are outlined in shapes of light, and in this vacancy he mapped out his local Heaven and Hell. Heaven, as Milton portrays it, is a plain of vast extent, diversified with hills, valleys, woods and streams. In the Second Book he speaks of it as-- Extended wide In circuit, undetermined square or round; in the Tenth Book it is determined, and is square. It is bounded by battlements of living sapphire, and towers of opal. In the midst is situated a Mount, the dwelling place of the Most High, surrounded by golden lamps, which diffuse night and day alternately--for without twilight and dawn, his dearest memories, Heaven would have been no Heaven to Milton. On a mountain far to the north of this great plain, Satan erects his pyramids and towers of diamond and gold, and establishes his empire, which lasts exactly three days. At his final overthrow the crystal wall of Heaven rolls back, disclosing a gap into the abyss; the rebels, tortured with plagues and thunder, fling themselves in desperation over the verge. They fall for nine days, through Chaos. Chaos is the realm of a king of the same name, who reigns over it with his consort Night. It is of immeasurable extent, quite dark, and turbulent with the raw material of the Cosmos. Just as Milton, for the purposes of his poem, followed the older astronomy, and gave to it a new lease of life in the popular imagination, so also he abides by the older physics. The orderly created World, or Cosmos, is conceived as compounded of four elements, Earth, Air, Fire, and Water. None of these four is to be found in Chaos, for each of them is composed of the simpler atoms of Hot, Cold, Moist, and Dry, symmetrically arranged in pairs. Thus Air is Hot and Moist, Fire is Hot and Dry, Water is Cold and Moist, Earth is Cold and Dry. Before they are separated and blended by Divine command, the four rudimentary constituents of creation are crowded in repulsive contiguity; they bubble and welter, fight and jostle in the dark, with hideous noises. In its upper strata Chaos is calmer, and is faintly lighted by the effulgence from the partially transparent walls of Heaven.