Figure and ornament, therefore, are not interchangeable terms; the loftiest figurative style most conforms to the precepts of gravity and chastity.  None the less there is a decorative use of figure, whereby a theme is enriched with imaginations and memories that are foreign to the main purpose.  Under this head may be classed most of those allusions to the world’s literature, especially to classical and Scriptural lore, which have played so considerable, yet on the whole so idle, a part in modern poetry.  It is here that an inordinate love of decoration finds its opportunity and its snare.  To keep the most elaborate comparison in harmony with its occasion, so that when it is completed it shall fall back easily into the emotional key of the narrative, has been the study of the great epic poets.  Milton’s description of the rebel legions adrift on the flaming sea is a fine instance of the difficulty felt and conquered: 

Angel forms, who lay entranced
Thick as autumnal leaves that strow the brooks
In Vallombrosa, where the Etrurian shades
High over-arched embower; or scattered sedge
Afloat, when with fierce winds Orion armed
Hath vexed the Red-Sea coast, whose waves o’erthrew
Busiris and his Memphian chivalry,
While with perfidious hatred they pursued
The sojourners of Goshen, who beheld
From the safe shore their floating carcases
And broken chariot-wheels.  So thick bestrown,
Abject and lost, lay these, covering the flood,
Under amazement of their hideous change.

The comparison seems to wander away at random, obedient to the slightest touch of association.  Yet in the end it is brought back, its majesty heightened, and a closer element of likeness introduced by the skilful turn that substitutes the image of the shattered Egyptian army for the former images of dead leaves and sea-weed.  The incidental pictures, of the roof of shades, of the watchers from the shore, and the very name “Red Sea,” fortuitous as they may seem, all lend help to the imagination in bodying forth the scene described.  An earlier figure in the same book of Paradise Lost, because it exhibits a less conspicuous technical cunning, may even better show a poet’s care for unity of tone and impression.  Where Satan’s prostrate bulk is compared to

that sea-beast Leviathan, which God of all his works Created hugest that swim the ocean-stream,

the picture that follows of the Norse-pilot mooring his boat under the lee of the monster is completed in a line that attunes the mind once more to all the pathos and gloom of those infernal deeps: 

while night Invests the sea, and wished morn delays.