At its most effective, the caesura allows a degree of movement simply unavailable in verse with only one kind of pause within it. It allows for levels of activity within the activity promised by the individual line. Moreover, the flexibility of the caesura allows for exchanges of position: midway through the line, when we anticipate a weak turn, we may experience a strong one, and the reverse can happen at the end of the line. The line can turn intense or grow slack, within itself, according to the poem as it is shaped.

The immense advantage of the variable caesura, then, is that it can orchestrate such a minor turn--not strong enough to deserve an entire line to itself yet indicating a distinct shift. Its inflection can be reserved for the turn that occurs within memory, the turn less active than the major turns unfolding as the poem develops. Although the caesura is exclusively associated with verse and related to the fundamental verse unit, the line break, it allows Merwin to borrow a feature from the spaciousness of prose: syntax can now be used adroitly, in the form of the prepositional phrase, to downplay turns, to render them less active.

One poem that draws on phrasings that might be considered weak, yet that serve to orchestrate the poet's feelings most precisely, is "Sun and Rain." In the first stanza, the last halves of the lines form around prepositional phrases, weak turns that present Merwin's movement back into the past "after five years." In general, active statements begin after the line break, honoring its greater authority ("I find that," "looking down," and "hearing the current") while the afterthoughts, the deepening downward pull towards the past, occur in prepositional phrases that follow the caesura. Merwin conveys the sudden downward spiral of being overtaken by a memory of sorrow; the softening into darkness is palpable as we move from "a bright window" to the image of his mother looking "at dusk into a river" and "hearing the current as hers."

Against this emerges the saving gesture of the second stanza-- hands held out for another and clinging to a long moment on the edge of death. The strength in the gesture is kept up in the forthright clauses that now begin to dominate and even spill over beyond the boundary of the caesura. This in turn leads back to the present, with the vivid movement of creatures that "turn uphill" in "a band of sunlight" and stand "as the dark rain touches them," as the hands of his mother and father once touched. It is a complex surrogate moment, in which Merwin's longing to reach out to his own mother is answered by this recollected moment in which his father had been able to overcome his own hesitancy to extend his hand to hers, and then comforted further by this encompassing vision of sun and rain mingling together. The vision is a gift much as his father's gesture was a gift to his mother: it keeps that gesture alive and recovers it for the present.