Stevenson's envoy begins like an invitation and ends like a ghost story. For most of its length it speaks warmly to a child reader, sprawled on a garden seat or tucked into a sofa corner, and tells them to open the book and step into "other lands." Only in the last few lines do we learn what is actually on the other side of the page: a child who can be seen but never reached.
The journey the poem promises is built from the ordinary stuff of a house. The reader is "hunting in the garden rows," or poking about in the attic or cellar, when they find "a nail-studded door / And dark, descending stairway" leading to "kingdoms underground." The setting is slightly gothic, but the sounds that follow are delightful: "strange birds a-singing," trees that "swing in big robber woods," bells on "fairy citadels." The speaker knows how this kind of make-believe works. It begins with "suppose," and he flags it with "as children feign." The aside "Neither mamma nor nurse need know!" makes the adult poet a fellow conspirator, and the references to Alice and Gerda (the heroine of Andersen's Snow Queen story, who sets off after her friend) place the book among the great travels of children's fiction.
The form carries this playfulness. The poem is written in rhyming couplets of eight-syllable lines, with a quick, bouncing beat that suits a nursery. The rhymes are simple and satisfying: seat and feet, hands and lands, ease and trees. Stevenson also lets the syntax run over the line ends. The sentence that begins "For lo!" tumbles through more than a dozen lines before it stops at "citadels," and the break in "or / The cellar" seems to drop the reader down the stairs. It sounds like a child telling a story at top speed, adding one more marvel before anyone can interrupt.
The turn comes with a clever reversal of looking. "As from the house your mother sees / You playing round the garden trees," says the speaker, and then he asks the reader to take the mother's place and look "through the windows of this book" at another child playing. The book is a window, and that means something seen through glass. The warning that follows is gentle but final: you cannot call to that child by "knocking on the window." Stevenson's language here becomes absorbed and slightly twisted, as the child is "intent / Is still on his play-business bent." The hyphenated "play-business" is a nice coinage. It treats play as a child's serious work, something too important to be interrupted. Then comes a run of short refusals: "He does not hear, he will not look, / Nor yet be lured out of this book."
The last four lines change the mood. "For long ago, the truth to say, / He has grown up and gone away" is almost entirely plain, one-syllable speech, and the casual filler "the truth to say" makes the news sound all the more matter-of-fact. What remains in the garden is only "a child of air" that "lingers." The word suggests something close to a ghost: present enough to be seen, too thin to be touched. Judging by these lines, the child on the other side of the glass is the grown-up speaker's own younger self, though the poem never says so outright.
That is what makes the envoy more than a cheerful farewell. By placing it at the end, Stevenson asks us to reread everything before it as memory. The games and gardens in the book are real as long as we read, but the child who lived in them cannot be summoned back. The poem also quietly turns the reader into a future adult. The "you" with raised feet on the garden seat is being told, without any lecture, that this too will pass. A children's book that admits the loss behind its own pleasures is rare, and it is the admission, delivered in a few light, rhymed lines, that gives the poem its lasting force.