The comparison of Satan's shield to the moon, for instance, is borrowed from the similar comparison of the shield of Achilles in the Iliad, but what goes in Homer comes out Milton.

Homer merely says that the huge and massy shield emitted a lustre like that of the moon in heaven.

Milton heightens the resemblance by giving the shield shape, calls in the telescope to endow it with what would seem preternatural dimensions to the naked eye, and enlarges even these by the suggestion of more than the telescope can disclose-- "His ponderous shield, Ethereal temper, massy, large, and round Behind him cast; the broad circumference Hung on his shoulders like the moon, whose orb Through optic glass the Tuscan artist views At evening, from the top of Fesole, Or in Valdarno, to descry new lands, Rivers or mountains in her spotty globe." Thus does Milton appropriate the wealth of past literature, secure of being able to recoin it with his own image and superscription.

The accumulated learning which might have choked the native fire of a feebler spirit was but nourishment to his.

The polished stones and shining jewels of his superb mosaic are often borrowed, but its plan and pattern are his own.
One of the greatest charms of "Paradise Lost" is the incomparable metre, which, after Coleridge and Tennyson have done their utmost, remains without equal in our language for the combination of majesty and music.
It is true that this majesty is to a certain extent inherent in the subject, and that the poet who could rival it would scarcely be well advised to exert his power to the full unless his theme also rivalled the magnificence of Milton's.