Most of the lines in "On My First Son"—three-quarters of them—are end-stopped. As a result, the poem generally feels slow, measured, and reflective. These long, pensive pauses give the reader a sense of Jonson’s mood as he meditates on his son’s death. Instead of rushing through his grief or trying to work his way toward resolution, he lingers on it—even wallows in it.
This is evident in the run of end-stopped lines that open the poem. All of the poem’s first four lines are end-stopped:
Farewell, thou child of my right hand, and joy;
My sin was too much hope of thee, lov'd boy.
Seven years thou'wert lent to me, and I thee pay,
Exacted by thy fate, on the just day.
As Jonson lays out the facts, meditates on his own “sin,” and describes the harsh terms of the loan he has been forced to repay, he pauses at the end of each line. These end-stops are heavy, ponderous. It almost feels like Jonson is having a hard time continuing the poem—as though he wants to give up at the end of each line.
Since these end-stops are so strong—and since they dominate the first four lines of the poem—they strongly shape the reader’s experience of the poem's rhythm, pace, and mood. The poem’s few enjambments feel like deviations from this rhythm, so the end-stopped lines that follow these enjambments feel less like closure and certainty and more like a return to despair. The reader can see this effect in lines 9-10, for instance:
Rest in soft peace, and, ask’d, say here doth lie
Ben Jonson his best piece of poetry.
The enjambment in line 9 creates a sense of expectation and uncertainty: the reader wonders how Jonson will characterize his son’s death, what he will choose as an epitaph. But then line 10—and its strong end-stop—feels like a return to the steady, almost monotonous despair of the rest of the poem. The return to firm end-stop suggests that it doesn't matter much what the epitaph is; Jonson's son is still dead, and nothing can change that.