The first 4 lines of “On My First Son” establish the poem’s themes and its form. The speaker of the poem is Ben Jonson himself; he is mourning the death of his first son, who died from the plague in 1603 when he was just seven years old. Jonson describes him as the “child of my right hand.” These words indicate that he hasn't lost just any child: he's lost his favorite child, the one he loved the most and put the most hope in. Indeed, he complains that he had “too much hope of thee, lov’d boy.” In other words, he had high expectations for his son, which makes his death all the sadder. An alliterative /h/ sound links together “hand” and “hope”—emphasizing the force and power of Jonson's hopes.
Even as Jonson mourns his son's death in powerful and affecting terms—unusual for a poet who is often biting and sarcastic—he also recognizes that human life is frail and fleeting. In lines 3-4, he describes human life as a metaphorical loan. His son was “lent to [him]. " The metaphor suggests that Jonson’s son doesn’t belong on earth; his true home is in Heaven. However, the sound of these lines suggests that Jonson has a hard time accepting this idea. Note the sharp and tough /t/ consonance in line 4:
Exacted by thy fate, on the just day.
It almost sounds like Jonson’s teeth are clenched, like he’s spitting out this line in frustration.
Lines 1-4 thus establish the poem as an elegy—a poem of mourning. Usually, elegies follow a set pattern or narrative. They start with a speaker deep in grief—but the speaker eventually finds consolation. Jonson’s elegy does begin with its speaker deep in mourning for his son. In the first four lines of the poem, Jonson focuses on his grief, wallowing in it. All of the first four lines of the poem are end-stopped, which makes them feel slow and ponderous, as though Jonson were dwelling on each detail of his grief, unable to let anything go.
Further, Jonson talks directly to his son—an instance of the poetic device apostrophe—as though he were still alive, negotiating, complaining, and rehearsing their relationship. The use of apostrophe suggests that he is having trouble letting go: he can't accept that his son is dead, even as he bids him "farewell." He loved his son too intensely to simply give him up. From the first lines, then, there is strong evidence to suggest that Jonson struggles to find consolation. Even though an elegy is supposed to comfort people in mourning, the author of this elegy cannot find a way to comfort himself: it seems that there is no consolation powerful enough to overcome this tragedy. And indeed, as the poem continues it will become clear that Jonson is breaking the elegy's usual pattern; he doesn’t succeed in finding a source of consolation that can soothe his despair.
The first four lines of “On My First Son” also establish the poem’s formal pattern. It is written in heroic couplets. In other words, each line of the poem is in iambic pentameter—a meter that features five poetic feet per line, in an unstressed-stressed da-DUM rhythm. Jonson deploys this meter consistently throughout, with the exception of a few ambiguous lines, like line 3. The lines also rhyme with each other in an AABB pattern. Heroic couplets are a distinguished form in English poetry; they are usually reserved for elevated topics, like heroic battles or serious philosophical disputes. But Jonson chooses to use the form here, for a poem about his personal grief. In doing so, he makes an implicit argument about his son’s death: it is as monumental an event as any battle; his son is as important as any hero.