Lycidas was written in November, 1637, and first appeared in 1638 in a student collection of verses commemorative of Edward King of Christ's College, Cambridge — "a fair poet, a good scholar, and a promising young clergyman" — who died in an unforeseen accident at sea in August of that year. The volume contained twenty-three poems in Latin and Greek and thirteen in English; Lycidas was the last of these.
The fourth son of Sir John King, Privy Councilor for Ireland and Secretary to the Irish Government, Edward King was admitted to Christ's College, Cambridge, in 1626, one year after Milton. As the number of students at the college was small and both King and Milton were assigned William Chappell as their tutor, the two doubtless met. However, Milton was 17 to King's 14, so the possibility of a close friendship developing between them, at least initially, was highly unlikely. Further, while King seems to have been universally admired for his learning and Milton must surely have shared in that admiration, there is no evidence to suggest that they ever came to know one another well — as well as Milton and Diodati.
Why then would Milton, who had left Cambridge five years before King's untimely death, have been invited to contribute to a college memorial collection? Very likely, his reputation as a poet had lingered over those years — how would it not have, after The Nativity Ode and L'Allegro and Il Penseroso. And then it is possible that news of his recent successes with Arcades and Comus had reached there, adding to that reputation.
In form, Lycidas is a pastoral elegy, where the central metaphor is the death of a shepherd-poet, who is pictured in an appropriately idyllic setting. With the pastoral elegy came certain conventions: the mourning of all nature for the loss of the shepherd-poet, and a sort of happy ending, where sadness momentarily turns to joy at the thought of the dead shepherd-poet's immortality. Included in the mourning section was usually a procession, in which each mourner expressed his grief in his own way, as well as some rhetorical questioning on the part of the "I" of those who were supposed to have watched over the shepherd-poet. The pastoral elegy was particularly prone to the inclusion of extraneous elements like the "I"'s own hopes and dreams, the reality of death, and seemingly unrelated political matters.
These features are all present in Lycidas. In the brief prologue (lines 1–22), the mourning motif is stated, including an anticipation of the "I"'s own death. Then follow three movements. In the first movement (lines 23–84), there is a reminiscence of life at Cambridge and a digression on the futility of artistic effort in the face of death. The second movement (lines 85–132) is given over to a procession of mourners — Triton, Herald of the Sea; Camus, representing Cambridge; and St Peter, Pilot of the Galilean lake — which leads into a digression on ecclesiastical corruption. In the third movement (lines 133–185), the "Vales and valleys low" are invoked to cast their flowers, and on line 165 comes the poem's emotional pivot from grief to joy at the thought that the dead shepherd-poet is in heaven. In the brief epilogue (lines 186–193), the mourner of the dead shepherd-poet looks forward to a new day and a future with some hope.
It is generally acknowledged that the grief in this poem, though somewhat muted or filtered, is palpable and seems genuine, and for lack of a real connection between Milton and King, it is customary to look elsewhere for its source. One possibility was the recent death of Milton's mother. Another is the fact of death, the fact, put squarely before Milton with King's accidental drowning at such an early age, that death could come at any time regardless of who one was and what one had invested in life.
Yet another possibility is that Milton, then in his 29th year, was undergoing the crisis that comes to so many of us at that time of life. Signs of such a crisis are perhaps present in Lycidas, Milton indeed looking back on the past with sadness and a sense of loss — "For we were nurst upon the self-same hill,/ Fed the same flock, by fountain, shade, and rill" — and certainly in the end looking forward to a resumption of life in a different context or continuum — "Tomorrow to fresh woods and pastures new."
Milton had numerous pastoral elegies as models from both classical antiquity and his own time, chiefly Theocritus's Idyll II, Moschus's Elegy on Bion, Bion's Lament for Adonis, Virgil’s Eclogues V and X, the pastorals of Petrarch, the November eclogue of Spenser's Shepherd’s Calendar, and Castiglione's Alcon.
Let Milton Scholar James Holly Hanford have the last word here:
The style, though always laden with ornament and allusion, varies with the mood, rising and falling, as Milton "somewhat loudly sweeps the string" in moments of exaltation and denunciation, or bids his Muse return again to the pastoral strain with its subdued note of tender melancholy. The analogy of music again occurs to mind as one considers the masterly way in which Milton has managed these fluctuations. No symphony was ever composed of more varied emotional elements or blended them more consummately into artistic unity.