Horace advises a Poet to consider thoroughly the Nature and Force of his Genius.  Milton seems to have known perfectly well, wherein his Strength lay, and has therefore chosen a Subject entirely conformable to those Talents, of which he was Master. As his Genius was wonderfully turned to the Sublime, his Subject is the noblest that could have entered into the Thoughts of Man. Every thing that is truly great and astonishing, has a place in it. The whole System of the intellectual World; the Chaos, and the Creation; Heaven, Earth and Hell; enter into the Constitution of his Poem.
Having in the First and Second Books represented the Infernal World with all its Horrors, the Thread of his Fable naturally leads him into the opposite Regions of Bliss and Glory.
If Milton's Majesty forsakes him any where, it is in those Parts of his Poem, where the Divine Persons are introduced as Speakers. One may, I think, observe that the Author proceeds with a kind of Fear and Trembling, whilst he describes the Sentiments of the Almighty. He dares not give his Imagination its full Play, but chuses to confine himself to such Thoughts as are drawn from the Books of the most Orthodox Divines, and to such Expressions as may be met with in Scripture. The Beauties, therefore, which we are to look for in these Speeches, are not of a Poetical Nature, nor so proper to fill the Mind with Sentiments of Grandeur, as with Thoughts of Devotion. The Passions, which they are designed to raise, are a Divine Love and Religious Fear. The Particular Beauty of the Speeches in the Third Book, consists in that Shortness and Perspicuity of Style, in which the Poet has couched the greatest Mysteries of Christianity, and drawn together, in a regular Scheme, the whole Dispensation of Providence, with respect to Man. He has represented all the abstruse Doctrines of Predestination, Free-Will and Grace, as also the great Points of Incarnation and Redemption, (which naturally grow up in a Poem that treats of the Fall of Man) with great Energy of Expression, and in a clearer and stronger Light than I ever met with in any other Writer. As these Points are dry in themselves to the generality of Readers, the concise and clear manner in which he has treated them, is very much to be admired, as is likewise that particular Art which he has made use of in the interspersing of all those Graces of Poetry, which the Subject was capable of receiving.
The Survey of the whole Creation, and of every thing that is transacted in it, is a Prospect worthy of Omniscience; and as much above that, in which Virgil has drawn his Jupiter, as the Christian Idea of the Supreme Being is more Rational and Sublime than that of the Heathens. The particular Objects on which he is described to have cast his Eye, are represented in the most beautiful and lively Manner.
Now had th' Almighty Father from above, (From the pure Empyrean where he sits High thron'd above all height) bent down his Eye, His own Works and their Works at once to view. About him all the Sanctities of Heavn Stood thick as Stars, and from his Sight received Beatitude past uttrance: On his right The radiant Image of his Glory sat, His only Son. On earth he first beheld Our two first Parents, yet the only two Of Mankind, in the happy garden plac'd, Reaping immortal fruits of Joy and Love; Uninterrupted Joy, unrival'd Love In blissful Solitude. He then surveyed Hell and the Gulph between, and Satan there Coasting the Wall of Heaven on this side Night, In the dun air sublime; and ready now To stoop with wearied wings, and willing feel On the bare outside of this world, that seem'd Firm land imbosom'd without firmament; Uncertain which, in Ocean or in Air. Him God beholding from his prospect high, Wherein past, present, future he beholds, Thus to his only Son foreseeing spake.
Satan's Approach to the Confines of the Creation, is finely imaged in the beginning of the Speech, which immediately follows. The Effects of this Speech in the blessed Spirits, and in the Divine Person to whom it was addressed, cannot but fill the Mind of the Reader with a secret Pleasure and Complacency.
Thus while God spake, ambrosial fragrance fill'd All Heavn, and in the blessed Spirits elect Sense of new Joy ineffable diffus'd. Beyond compare the Son of God was seen Most glorious, in him all his Father shone Substantially expressed, and in his face Divine Compassion visibly appeared, Love without end, and without measure Grace.
I need not point out the Beauty of that Circumstance, wherein the whole Host of Angels are represented as standing Mute; nor shew how proper the Occasion was to produce such a Silence in Heaven. The Close of this Divine Colloquy, with the Hymn of Angels that follows upon it, are so wonderfully Beautiful and Poetical, that I should not forbear inserting the whole Passage, if the Bounds of my Paper would give me leave.
No sooner had th' Almighty ceas'd, but all The multitudes of Angels with a shout (Loud as from numbers without number, sweet As from blest Voices) uttring Joy, Heavn rung With Jubilee, and loud Hosannas fill'd Th' eternal regions; &c. &c.--
Satan's Walk upon the Outside of the Universe, which, at a Distance, appeared to him of a globular Form, but, upon his nearer Approach, looked like an unbounded Plain, is natural and noble: As his Roaming upon the Frontiers of the Creation between that Mass of Matter, which was wrought into a World, and that shapeless unformed Heap of Materials, which still lay in Chaos and Confusion, strikes the Imagination with something astonishingly great and wild. I have before spoken of the Limbo of Vanity, which the Poet places upon this outermost Surface of the Universe, and shall here explain my self more at large on that, and other Parts of the Poem, which are of the same Shadowy Nature.
Aristotle observes, that the Fable of an Epic Poem should abound in Circumstances that are both credible and astonishing; or as the French Criticks chuse to phrase it, the Fable should be filled with the Probable and the Marvellous. This Rule is as fine and just as any in Aristotle's whole Art of Poetry.
If the Fable is only Probable, it differs nothing from a true History; if it is only Marvellous, it is no better than a Romance. The great Secret therefore of Heroic Poetry is to relate such Circumstances, as may produce in the Reader at the same time both Belief and Astonishment. This is brought to pass in a well-chosen Fable, by the Account of such things as have really happened, or at least of such things as have happened according to the received Opinions of Mankind. Milton's Fable is a Masterpiece of this Nature; as the War in Heaven, the Condition of the fallen Angels, the State of Innocence, and Temptation of the Serpent, and the Fall of Man, though they are very astonishing in themselves, are not only credible, but actual Points of Faith.
The next Method of reconciling Miracles with Credibility, is by a happy Invention of the Poet; as in particular, when he introduces Agents of a superior Nature, who are capable of effecting what is wonderful, and what is not to be met with in the ordinary course of things. Ulysses's Ship being turned into a Rock, and Æneas's Fleet into a Shoal of Water Nymphs; though they are very surprising Accidents, are nevertheless probable, when we are told that they were the Gods who thus transformed them. It is this kind of Machinery which fills the Poems both of Homer and Virgil with such Circumstances as are wonderful, but not impossible, and so frequently produce in the Reader the most pleasing Passion that can rise in the Mind of Man, which is Admiration. If there be any Instance in the Æneid liable to Exception upon this Account, it is in the Beginning of the Third Book, where Æneas is represented as tearing up the Myrtle that dropped Blood. To qualifie this wonderful Circumstance, Polydorus tells a Story from the Root of the Myrtle, that the barbarous Inhabitants of the Country having pierced him with Spears and Arrows, the Wood which was left in his Body took Root in his Wounds, and gave Birth to that bleeding Tree. This Circumstance seems to have the Marvellous without the Probable, because it is represented as proceeding from Natural Causes, without the Interposition of any God, or other Supernatural Power capable of producing it. The Spears and Arrows grow of themselves, without so much as the Modern Help of an Enchantment. If we look into the Fiction of Milton's Fable, though we find it full of surprizing Incidents, they are generally suited to our Notions of the Things and Persons described, and tempered with a due Measure of Probability. I must only make an Exception to the Limbo of Vanity, with his Episode of Sin and Death, and some of the imaginary Persons in his Chaos. These Passages are astonishing, but not credible; the Reader cannot so far impose upon himself as to see a Possibility in them; they are the Description of Dreams and Shadows, not of Things or Persons. I know that many Criticks look upon the Stories of Circe, Polypheme, the Sirens, nay the whole Odyssey and Iliad, to be Allegories; but allowing this to be true, they are Fables, which considering the Opinions of Mankind that prevailed in the Age of the Poet, might possibly have been according to the Letter. The Persons are such as might have acted what is ascribed to them, as the Circumstances in which they are represented, might possibly have been Truths and Realities. This Appearance of Probability is so absolutely requisite in the greater kinds of Poetry, that Aristotle observes the Ancient Tragick Writers made use of the Names of such great Men as had actually lived in the World, tho the Tragedy proceeded upon Adventures they were never engaged in, on purpose to make the Subject more Credible. In a Word, besides the hidden Meaning of an Epic Allegory, the plain litteral Sense ought to appear Probable. The Story should be such as an ordinary Reader may acquiesce in, whatever Natural, Moral, or Political Truth may be discovered in it by Men of greater Penetration.
Satan, after having long wandered upon the Surface, or outmost Wall of the Universe, discovers at last a wide Gap in it, which led into the Creation, and is described as the Opening through which the Angels pass to and fro into the lower World, upon their Errands to Mankind. His Sitting upon the Brink of this Passage, and taking a Survey of the whole Face of Nature that appeared to him new and fresh in all its Beauties, with the Simile illustrating this Circumstance, fills the Mind of the Reader with as surprizing and glorious an Idea as any that arises in the whole Poem. He looks down into that vast Hollow of the Universe with the Eye, or (as Milton calls it in his first Book) with the Kenn of an Angel. He surveys all the Wonders in this immense Amphitheatre that lye between both the Poles of Heaven, and takes in at one View the whole Round of the Creation.
His Flight between the several Worlds that shined on every side of him, with the particular Description of the Sun, are set forth in all the Wantonness of a luxuriant Imagination. His Shape, Speech and Behaviour upon his transforming himself into an Angel of Light, are touched with exquisite Beauty. The Poets Thought of directing Satan to the Sun, which in the vulgar Opinion of Mankind is the most conspicuous Part of the Creation, and the placing in it an Angel, is a Circumstance very finely contrived, and the more adjusted to a Poetical Probability, as it was a received Doctrine among the most famous Philosophers, that every Orb had its Intelligence; and as an Apostle in Sacred Writ is said to have seen such an Angel in the Sun. In the Answer which this Angel returns to the disguised evil Spirit, there is such a becoming Majesty as is altogether suitable to a Superior Being. The Part of it in which he represents himself as present at the Creation, is very noble in it self, and not only proper where it is introduced, but requisite to prepare the Reader for what follows in the Seventh Book.
I saw when at his Word the formless Mass, This Worlds material Mould, came to a Heap: Confusion heard his Voice, and wild Uproar Stood rul'd, stood vast Infinitude confin'd. Till at his second Bidding Darkness fled, Light shon, &c.
In the following Part of the Speech he points out the Earth with such Circumstances, that the Reader can scarce forbear fancying himself employed on the same distant View of it.
Look downward on the Globe whose hither Side With Light from hence, tho but reflected, shines; That place is Earth, the Seat of Man, that Light His Day, &c.
I must not conclude my Reflections upon this Third Book of Paradise Lost, without taking Notice of that celebrated Complaint of Milton with which it opens, and which certainly deserves all the Praises that have been given it; tho as I have before hinted, it may rather be looked upon as an Excrescence, than as an essential Part of the Poem. The same Observation might be applied to that beautiful Digression upon Hypocrisie, in the same Book.
[Footnote 1: De Arte Poetica. II. 38-40.]
[Footnote 2: Poetics, iii. 4.
The surprising is necessary in tragedy; but the Epic Poem goes farther, and admits even the improbable and incredible, from which the highest degree of the surprising results, because there the action is not seen.]