I have just spent a rather frustrating fifteen minutes trying to find the section that you refer to according to your line references, but cannot, so I assume you are referring to the end of Book III of this epic poem when Satan in disguise asks Uriel where Earth is. Uriel, in his description of God's new creation explains the kind of order that exists on earth:
Look downward on that globe whose hither side
With light from hence, though but reflected, shines;
That place is earth the seat of man, that light
His day, which else as th'other hemisphere
Night would invade, but there the neighbouring moon
(So call that opposite fair star) her aid
Timely interposes, and her monthly round
Still ending, still renewing, through mid heav'n,
With borrowed light her countenance triform
Hence fills and empties to enlighten th'earth,
And in her pale dominion checks the night.
Clearly this great description points towards the order that God make out of chaos in this new world, and suggests the planets that he has set in their course and his design that ensures "night" does not "invade" the earth, and the powers of darkness are "checked" by both the moon and the sun. It is evident that the creation of earth is a result of no accident, as at God's voice, "order from disorder sprung" with each star "in its place appointed, each his course." God's direction and design is something that is emphasises again and again in this passage.