—­Thus with ten Wounds
  The River-Dragon tamed at length submits
  To let his Sojourners depart, and oft
  Humbles his stubborn Heart; but still as Ice
  More harden’d after Thaw, till in his Rage
  Pursuing whom he late dismissed, the Sea
  Swallows him with his Host, but them lets pass
  As on dry Land between two Chrystal Walls,
  Aw’d by the Rod of Moses so to stand
  Divided—­

The River-Dragon is an Allusion to the Crocodile, which inhabits the Nile, from whence Egypt derives her Plenty.  This Allusion is taken from that Sublime Passage in Ezekiel, Thus saith the Lord God, behold I am against thee, Pharaoh King of Egypt, the great Dragon that lieth in the midst of his Rivers, which hath said, my River is mine own, and I have made it for my self.  Milton has given us another very noble and poetical Image in the same Description, which is copied almost Word for Word out of the History of Moses.

  All Night he will pursue, but his Approach
  Darkness defends between till morning Watch;
  Then through the fiery Pillar and the Cloud
  God looking forth, will trouble all his Host,
  And craze their Chariot Wheels:  when by command
  Moses once more his potent Rod extends
  Over the Sea:  the Sea his Rod obeys: 
  On their embattell’d Ranks the Waves return
  And overwhelm their War—­

As the principal Design of this Episode was to give Adam an Idea of the Holy Person, who was to reinstate human Nature in that Happiness and Perfection from which it had fallen, the Poet confines himself to the Line of Abraham, from whence the Messiah was to Descend.  The Angel is described as seeing the Patriarch actually travelling towards the Land of Promise, which gives a particular Liveliness to this part of the Narration.

  I see him, but thou canst not, with what Faith
  He leaves his Gods, his Friends, his Native Soil,
  Ur of Chaldaea, passing now the Ford
  To Haran, after him a cumbrous Train
  Of Herds and Flocks, and numerous Servitude,
  Not wand’ring poor, but trusting all his Wealth
  With God, who call’d him, in a Land unknown. 
  Canaan he now attains, I see his Tents
  Pitch’d about Sechem, and the neighbouring Plain
  Of Moreh, there by Promise he receives
  Gifts to his Progeny of all that Land,
  From Hamath Northward to the Desart South. 
  (Things by their Names I call, though yet unnamed.)

As Virgil’s Vision in the sixth AEneid probably gave Milton the Hint of this whole Episode, the last Line is a Translation of that Verse, where Anchises mentions the Names of Places, which they were to bear hereafter.

  Haec tum nomina erunt, nunc sunt sine nomine terrae.

The Poet has very finely represented the Joy and Gladness of Heart which rises in Adam upon his discovery of the Messiah.  As he sees his Day at a distance through Types and Shadows, he rejoices in it:  but when he finds the Redemption of Man compleated, and Paradise again renewed, he breaks forth in Rapture and Transport;