On a sudden open fly,
With impetuous recoil and jarring sound,
The infernal doors, and on their hinges grate
Harsh thunder, that the lowest bottom shook
Of Erebus.
But there are many more delicate instances than these. In the choruses of Samson Agonistes, where he reaches the top of his skill, Milton varies even the length of the line. So he has hardly a rule left, save the iambic pattern, which he treats merely as a point of departure or reference, a background or framework to carry the variations imposed upon it by the luxuriance of a perfectly controlled art. The great charm of the metre of Wither, which Charles Lamb admired and imitated, lies in its facile combination of what, for the sake of brevity, may be called the iambic and trochaic movements. In L'Allegro and Il Penseroso Milton had proved his mastery of both its resources. The gaiety of these lines--
Haste thee, Nymph, and bring with thee
Jest, and youthful Jollity--
passes easily into the solemnity of these--
But let my due feet never fail