urn swift their various motions, or are turned
By his magnetic beam, that gently warms
The Universe, and to each inward part
With gentle penetration, though unseen,
Shoots invisible virtue even to the Deep;
So wondrously was set his station bright.--iii. 552-87.

The Ptolemaic cosmology having been adopted by Milton in the elaboration
of his poem, he describes the universe in conformity with the doctrines
associated with this form of astronomical belief. To each of the first
seven spheres which revolved round the steadfast Earth there was
attached a heavenly body; the eighth sphere embraced all the fixed
stars, a countless multitude; the ninth the crystalline; and enclosing
all the other spheres as if in a shell was the tenth sphere, or Primum
Mobile, which in its diurnal revolution carried round with it all the
other spheres. The nine inner spheres were transparent, but the tenth
was an opaque solid shell-like structure, which enclosed the new
universe and constituted the boundary between it and Chaos underneath
and the Empyrean above. It was on the surface of this sphere that Satan
wandered until he discovered the opening at its zenith, where, by means
of a staircase or ladder, communication was maintained with the
Empyrean. Standing on the lower steps of this structure he paused for a
moment to look down into the glorious universe which lay beneath him--

another Heaven
From Heaven-gate not far, founded in view
On the clear hyaline the glassy sea.--vii. 617-19.

He beholds it in all its dimensions, from pole to pole, and
longitudinally from Libra to Aries, then without hesitation precipitates
himself down into the world's first region, and winds his way with ease
among the fixed stars. Around him he sees innumerable shining worlds,
sparkling and glittering in endless profusion over the circumscribed
immensity of space--mighty constellations that shone from afar;
clustering aggregations of stars; floating islands of light; twinkling
systems rising out of depths still more profound, and a zone luminous
with the light of myriads of lucid orbs verging on the confines of the
universe. All these worlds the fiend passed unheeded, nor stayed he to
inquire who dwelt happy there. In splendour above them all the Sun
attracted his attention and, directing his course towards the great
luminary of our system, he alights on the surface of the orb.

Milton now makes