"Silly boy, silly Billy" sounds like a scolding that is really a caress. Someone is addressing a boy out on a dark hill in bad weather, half teasing and half frightened for him. The poem's central idea is how love sounds when it is afraid. The speaker never shouts "come home". Instead the voice coaxes, rearranges the storm into something friendly, and only in the last line lets the fear show.
That rearranging happens in the first stanza. "Thunder's for company, / Rain is for thirst" is a tidy little list in which each piece of weather is given a kindly job. Thunder keeps the boy company, and rain quenches his thirst. Then the grammar changes. "Lightning to show the path" drops the "is for" altogether, so the line leans forward and tips the reader downhill, "Down to the valley." The speaker is reassuring, but also steering. Every comfort on offer points the same way, away from the hill.
The valley is the poem's most interesting image. Its "rivulets spill / Limpid monotony", an oddly beautiful phrase. "Limpid" means clear and untroubled, "monotony" means sameness, and the two sit together like a gentle contradiction. The sound enriches it too: the liquid l's of "rivulets," "spill," "limpid" and "valley" ripple through the lines as if the words were running water. Safety here is clear but dull. That may be why Billy is "silly". The hill is dark and dangerous, but it is not monotonous, and the poem seems to understand why a boy might prefer it.
The title, "Rhyme", invites us to look at the sound. The poem has a nursery-rhyme lilt (short lines, repeated names, a sing-song "Billy boy"), but it rarely rhymes in the tidy way a nursery rhyme does. Instead it echoes. "Silly," "Billy," "hill" and "spill" form an -ill chain that stretches across two stanzas. "Company," "valley," "monotony" and "tree" share a soft, unstressed -ee sound, and "oh" in line ten answers "go" in the last. Notice what lacks a partner: "thirst" and "path," the words for need and for direction, stand unrhymed and a little exposed. The poem chimes often but never quite clicks shut, which suits a speaker who cannot be certain of a happy ending. The rhythm behaves similarly. Lines swing between two and three strong beats ("On the dark hill" is almost all stress), so the singsong keeps stumbling and recovering.
The last stanza is where the voice breaks. "Oh for my Billy boy!" is grammatically unfinished: oh for what? A wish for his safety, his return, his company? It is also the first time the speaker says "my," and the first time the feeling is claimed outright. Then Billy's name is turned inside out, "Billy boy oh!", so that it becomes a cry across a hillside rather than a label. The closing command, "Under the apple tree, / There do not go," uses the odd, inverted word order of a charm or a superstition. The poem gives no reason. Judging by the imagery, one plausible reading is practical, since a tree is a poor shelter when lightning is about, and lightning has just been called the boy's guide. Another is that the apple tree is simply a place of temptation or lingering. The poem leaves both possible, and its silence about why makes the warning feel more urgent.
What makes the poem worth reading is that contrast between sweet form and uneasy content. In twelve short lines it uses the language of the nursery, which we associate with safety, to carry a fear that never quite names itself. It also leaves the ending open. We never learn whether Billy listens, whether he is even within earshot, or whether the speaker is calling after someone already gone. That uncertainty is what stays in the mind, like a tune you cannot finish humming.