Methought I saw my late espoused saint Brought to me, like Alcestis, from the grave, Whom Jove's great son to her glad husband gave, Rescu'd from death by force, though pale and faint.
The poem recounts a dream vision in which the speaker saw his wife return to him (as the dead Alcestis appeared to her husband Admetus), only to see her disappear again as day comes.
Samuel Johnson, in the Lives of the Most Eminent English Poets, suggests his second wife, Katherine Woodcock, and comments that "her husband honoured her memory with a poor sonnet".
Leo Spitzer in 1951 was one of the first to suggest a tripartite structure, subsequently agreed upon and expanded by other critics: the imagery in the sonnet moves from Greek history and mythology (the reference to Alcestis) through Jewish law (the purification mandated by the "old Law"), to Christian salvation, one critic describing the movement as "a progressive definition of salvation".
[5] According to John Spencer Hill, this particular structure is typical of Milton's later writings: he sees it in Books IV and V (Proserpine-Eve-Mary) and Books XI and XII (Deucalion-Noah-Christ) of Paradise Lost, and in Samson Agonistes (Hercules-Samson-Christ): the triptychs, whose figures are taken successively, do not just complement each other; cumulatively they present an organic process toward spiritual fulfillment in the antitype.