“The kingdom of heaven cometh not with observation.”  We know but little of the history of the greatest works of genius.  That something more than usual should be known of “Paradise Lost” must be ascribed to the author’s blindness, and consequent dependence upon amanuenses.  When inspiration came upon him any one at hand would be called upon to preserve the precious verses, hence the progress of the poem was known to many, and Phillips can speak of “parcels of ten, twenty, or thirty verses at a time.”  We have already heard from him that Milton’s season of inspiration lasted from the autumnal equinox to the vernal:  the remainder of the year doubtless contributed much to the matter of his poem, if nothing to the form.  His habits of composition appear to be shadowed forth by himself in the induction to the Third Book:—­

   “Thee, Sion, and the flowery brooks beneath
    That wash thy hallowed feet, and warbling flow,
    Nightly I visit—­”

   “Then feed on thoughts that voluntary move
    Harmonious numbers; as the wakeful bird
    Sings darkling, and in shadiest covert hid
    Tunes her nocturnal note.”

This is something more precise than a mere poetical allusion to his blindness, and the inference is strengthened by the anecdote that when “his celestial patroness” “Deigned nightly visitation unimplored,” his daughters were frequently called at night to take down the verses, not one of which the whole world could have replaced.  This was as it should be.  Grand indeed is the thought of the unequalled strain poured forth when every other voice was hushed in the mighty city, to no meaner accompaniment than the music of the spheres.  Respecting the date of composition, we may trust Aubrey’s statement that the poem was commenced in 1658, and when the rapidity of Milton’s composition is considered ("Easy my unpremeditated verse”) it may, notwithstanding the terrible hindrances of the years 1659 and 1660, have been, as Aubrey thinks, completed by 1663.  It would still require mature revision, which we know from Ellwood that it had received by the summer of 1665.  Internal evidence of the chronology of the poem is very scanty.  Professor Masson thinks that the first two books were probably written before the Restoration.  In support of this view it may be urged that lines 500-505 of Book i. wear the appearance of an insertion after the Restoration, and that in the invocation to the Third Book Milton may be thought to allude to the dangers his life and liberty had afterwards encountered, figured by the regions of nether darkness which he had traversed as a poet.

   “Hail holy Light!... 
    Thee I revisit now with bolder wing,
    Escaped the Stygian pool, though long detained
    In that obscure sojourn, while in my flight
    Through utter and through middle darkness borne.”

The only other passage important in this respect is the famous one from the invocation to the Seventh Book, manifestly describing the poet’s condition under the Restoration:—­