burning lake, drowsed by
its fumes, the World was created. It consists, according to the astronomy
followed by Milton, of ten concentric spheres fitted, like Chinese boxes,
one within another, and the Earth in the centre. Nine of these are
transparent, the spheres, that is to say, of the seven planets (the Sun
and the Moon being reckoned as planets), the sphere of the fixed stars,
and the crystalline sphere. The outermost sphere, or _primum mobile_, is
opaque and impervious. The whole orbicular World hangs by a golden chain
from that part of the battlements of Heaven whence the angels fell. It is
connected with Heaven by richly jewelled stairs, to be let down or taken
up at pleasure, and can be entered only through an orifice or passage at
the top. Between the foot of the stairs and the entrance to the World is
a sea or lake of jasper and liquid pearl.

All the interest and meaning of the World is centred in one favoured spot
of Earth. Eden is a district of Mesopotamia, and the happy garden, called
Paradise, is situated in the east of Eden. It is a raised table-land,
surrounded on all sides by a high ridge of hill, thickly wooded, and
impenetrable. Its single gate, hewn out of a rock of alabaster, faces
eastward, and is accessible only by a pass leading up from the plain and
overhung by craggy cliffs. Through Eden runs a river which passes by a
tunnel under Paradise, and, rising through the porous earth, waters the
garden with springs. It was by this underground passage that Satan
entered the garden a second time, when, having been discovered by
Ithuriel, and expelled by Gabriel, he had circled the Earth seven times,
keeping on the shady side to avoid the gaze of Uriel, and at the end of
the week had resolved on another attempt.

The Fall of Man wrought some few changes in the physical configuration of
the Universe. Sin and Death built the mighty causeway that connects the
orifice of the World with Hell-gates. Provision had to be made under the
new dispensation for the peopling of the whole surface of the Earth; so
the axis was turned askew, and the beginning ordained of extremes of cold
and heat, of storms and droughts, and noxious planetary influences. Night
and day were known to man in his sinless state, but the seasons date from
his transgression.

The time-scheme of the poem is less carefully defined; indeed, it is not
certain that Milton intended accurately to define it. The recurrence of
the numbers three and