Among the difficulties in understanding the cosmological features of the poem is why Milton finds it necessary to discuss so often a subject that requires suspension of the action of the poem. One of Milton's favorite authors, Ovid, found no such need for cosmology in the often Christianized first book of the Metamorphoses. Neither did Lucretius, Dante, or Spenser. One explanation holds that in Books 7–8, Milton sought to provide a positive counterpart at the beginning of the second half (of the twelve-book version) to the War in Heaven ending the first half. That may well be, but it does not explain why the topic should be so important elsewhere.
To lend what clarity is possible, we shall define Milton's cosmology as knowledge of the world or worlds and so inclusive of astronomies, systems of ordering the earth, sun, and planets. We see that the astronomies of his time—Ptolemaic, Tyconian, Copernican—lack the importance of cosmology and that his usage of “world” and “worlds” is often unclear.
This discussion therefore begins with two passages easily ignored in considering issues of the universe depicted by Milton. In the first (8.128–36), Raphael is rehearsing some of the details of astronomical alternatives that confused seventeenth-century minds and are no clearer when we read them now.
what if sev'nth to these The Planet Earth, so stedfast though she seem, Insensibly three different Motions move? Which else to several Sphears thou must ascribe, Mov'd contrarie with thwart obliquities, Or save the Sun his labour, and that swift Nocturnal and Diurnal rhomb suppos'd, Invisible else above all Starrs, the Wheele Of Day and Night; which needs not thy beleefe …
In remarkably few words, these eight lines give a full sense of alternatives Milton insists upon but whose necessity to the poem is not evident. And, with whatever exasperation Milton also conveys, that is also its point. “What if …?” What difference does it all make? And then that closing dry mock of irony, “which needs not thy beleefe.” The real, the actual, or the true is just as it is, independent of our belief.
It is therefore all the more remarkable that Milton himself seems unable to leave the subject untended. Why indeed are cosmology and astronomy subjects of the poem? The answer comes in a breathtaking but more familiar passage in Book 7. God is speaking to the Son about Satan's rebellion and the threat Satan may suppose that poses.
But least his heart exalt him in the harme Already done, to have dispeopl'd Heav'n My damage fondly deem'd, I can repaire That detriment, if such it be to lose Self-lost, and in a moment will create Another world … (7.150–55)
Milton can only have calculated the effect of this seemingly offhand remark: we are meant to be impressed.
There are those first three words, “In a moment I will create another world.” The literal-minded objection to that is obviously that the “moment” extends in Book 7 over at least lines 216 to 549:
Silence, ye troubl'd waves, and thou Deep, peace. Said then th' Omnific word, your discord end … Here finish'd hee, and all that he had made View'd, and behold all was entirely good.
That objection to a moment of six days and more than three hundred lines is of course answered in advance by Raphael:
Immediate are the Acts of God, more swift Then time or motion, but to human ears Cannot without process of speech be told, So told as earthly notion can receave. (7.176–79)
One surprising thing remains. Our Protestant literalist in matters of biblical interpretation somehow incorporates the six days of the biblical account with his own story as an accommodation for human powers to comprehend. Milton implies here an almost Calvinistic application of divine omnipotence to make “a moment” of the hexaemeron in Genesis 1.
God also says that in that moment he will “create another world.” The clear sense is obviously that he had