The title that Henry Wadsworth Longfellow (1807–1882) chose for his 1875 graduation poem was “Morituri Salutamus” — derived from the ancient gladiators’ call, Ave Imperator, morituri te salutant: “Hail, Caesar. We who are about to die salute you.” In Longfellow’s hands, however, it comes from old men, attending the 50th anniversary of their graduation, to those about to receive their diplomas and enter the world: “Young men, whose generous hearts are beating high, / We who are old, and are about to die, / Salute you . . . ”

Here in the spring season of college and high-school graduation, The New York Sun is offering a week’s worth of graduation poems. And the first of these Poems of the Day almost has to be, by rights, a passage from Longfellow’s 284-line “Poem for the Fiftieth Anniversary of the Class of 1825 in Bowdoin College.” That college in Maine was a serious place, in those days, with Nathaniel Hawthorne and Longfellow both in the class of 1825, and the future president, Franklin Pierce, a friend just a year ahead of them.

Hawthorne died in 1864 and Pierce in 1869, both before their 50th college anniversary (“my classmates; ye remaining few, / That number not the half of those we knew”). Still, Longfellow’s Trojan image of old men watching from the city wall as the young warriors march out — “So from the snowy summits of our years / We see you in the plain” — forms a perfect analogy, as the poet deploys his heroic couplets, his five-foot lines rhymed in pairs, to remember the past — both to encourage the new generation rising up to take the place of their predecessors, and to urge the old not yet to surrender to lassitude and melancholy.