A lullaby is meant to keep a child where she is, and Tennyson's "Cradle Song" seems to do just that. It coaxes, it soothes, it asks for a little more time. Yet every word of persuasion carries a quiet admission that time is the one thing the speaker cannot keep. The poem sets a nestling beside a baby. Each wakes at dawn, each wants to "fly away," and each is told by a mother to wait until she is stronger. The central idea is that growing up is a kind of leaving, and that to love a child is to tend someone who is meant to go.
The two stanzas are built as mirror images, and the small changes between them carry the meaning. The first asks what the bird says "in her nest at peep of day"; the second asks what the baby says "in her bed at peep of day." The bed becomes a nest, so the cot is quietly turned into a place from which flight is expected. "Wings" becomes "limbs," which gives the baby the bird's ambition without the bird's equipment, and so "fly" shifts into a metaphor for independence. "Rest" becomes "sleep." The bird is the example, and the baby is the case it illustrates.
The sound of the poem is the sound of rocking. Most lines follow a trochaic beat, strong then weak: "WHAT does LITtle BIRdie SAY." Many lines then drop the final weak syllable, so that "In her nest at peep of day" ends on a stressed word, like a cradle reaching the end of its swing. The rhyme pattern, as I read it, runs A A B A C C C A. The sounds of "say," "day" and "away" return like a refrain and make the stanza feel closed and safe. Then "longer" and "stronger" chime together, and "longer" is repeated, so the line stretches just as the mother is stretching the morning. The one line that stands outside the pattern is the third, the line that brings in the young creature's own voice, as if that wish cannot be fitted neatly into the mother's soothing music.
The vocabulary is as small and soft as the subject. "Little" appears again and again, along with "birdie" and "baby," and the effect is nursery warmth. But "a little longer" is a modest request, and the repetition suggests the mother knows how little she can really ask for. Then there is "thy," slightly old-fashioned, which makes her tenderness sound intimate and a touch solemn. "Peep of day" works twice, since it is the first glimpse of light and also close to the cheep of a waking bird. When the baby asks to "rise," the word covers waking up and lifting off, and it is hard to separate the two.
The ending is where the lullaby shows its edge. The bird's story is told plainly and in the past: "So she rests a little longer, / Then she flies away." There is no fuss, only a pause and then the departure. The baby's version is hedged with a condition: "If she sleeps a little longer." That "if" sounds like bargaining, as though sleep were the price of a few more days. Yet the verb that follows is "shall," which is firm and leaves no room for doubt. And the quietest word in the poem is "too." It takes a gentle comparison and turns it into a forecast: the baby will do exactly what the bird does.
What makes the poem worth reading is how much feeling it fits into such a slight form. A child can enjoy it as a bouncing rhyme about a bird. An adult hears the mother's patience and her sadness in the same breath, because every "a little longer" she offers is also a step toward the "away" she can see coming. The poem comforts the child by describing the very thing the parent dreads, and it does so without once raising its voice.