Milton's casual use of the word “vicissitude” provides a simple measure of our differences from him and of our difficulty with his epic. At the opening of Book VI of Paradise Lost occurs a descriptive passage of relaxed intensity:

There is a Cave
Within the Mount of God, fast by his Throne,
Where light and darkness in perpetual round
Lodge and dislodge by turns, which makes through Heav'n
Grateful vicissitude, like Day and Night. (4-8)

The phrase “Grateful vicissitude” delays or shocks almost any modern reader, for whatever our dictionary-makers say, it has been many years since “vicissitude” was used in ordinary English speech or writing in other than a pejorative sense. In Paradise Lost, however, “vicissitude” is always “grateful;” it is change, variety, movement, the mark of vitality and joy characteristic of both the divine and the human master artist's work. We cannot properly read the poem unless we can share imaginatively, at least for the moment, Milton's conception.