A sunny morning, birdsong and clean air: Stevenson's "Spring Song" opens like a greeting card, then asks whether the card is telling the truth. In twelve lines the speaker catches himself falling back into love, and ends with a rueful suspicion that the season may have fooled him.
The order of events matters. In the first stanza the weather arrives first: "The air was full of sun and birds." Only then does something stir inside: "Remembrance wakened in my heart / And I knew I loved her dearly." The speaker doesn't decide he loves her. He *knows* it after the feeling has already arrived, as if reading his own heart for the first time. The poem never says who "her" is or where she is, but "remembrance" suggests she is absent and the feeling is being summoned by the day. The second stanza ties world and body closer together. The landscape is not yet lush, only "the fallows and the leafless trees", empty fields and bare branches. This is early spring, a beginning rather than a finished thing, and the words "earliest" and "First" in the next lines make the same point about the feeling. Then the senses take over. The spirit "tingled", and "My earliest thought of love, and Spring's / First puff of perfume mingled." Smell is the sense most closely bound to memory, and the poem seems to understand that without announcing it.
The form is as light as the mood. Only the second and fourth lines of each stanza rhyme, and all three rhymes are double: *clearly/dearly*, *tingled/mingled*, *together/weather*. That soft two-syllable landing gives the poem a lilt, like something half-sung, which suits a "song". The pairs also work on the meaning. "Clearly" and "dearly" link clear air to a clear heart. "Tingled" and "mingled" fuse physical sensation with the blending of scent and thought. The final pair joins the gathering of feelings to the weather, so the closing question sounds like a rhyme that has made up its own mind. The rhythm is a quick four-beat line, mostly iambic, that nearly skips in "And I knew I loved her dearly." The vocabulary stays plain and mostly short: *air, sun, birds, heart, love*. Nothing is dressed up, and that makes the doubt at the end land harder.
The third stanza turns inward. "In my still heart" makes the heart sound like frozen ground, and "awoke" echoes "wakened" from the first stanza, so the heart becomes a sleeper stirred by the warmth. Then comes the strangest phrase in the poem: "Came lone by lone together." It twists the familiar "one by one" so that each thought arrives alone yet ends up in company. The paradox suits a mind slowly collecting its own feelings. A dash follows, and the speaker turns to question the birds, Sun and Spring directly. The capital letters make them witnesses, almost suspects.
The question itself is where the poem is cleverest: "is Love / A mere affair of weather?" The line break leaves "Love" hanging for a moment before "mere affair" deflates it. "Affair" also carries its everyday romantic sense, so the phrase sets love's own vocabulary against it.
The poem is worth reading because it refuses to answer. One reading is cynical: if sunshine and a whiff of blossom can produce devotion, perhaps the devotion is only a mood. The other is warmer: if love comes as naturally and unbidden as the seasons, it may be no less real for that. The speaker's tone, half delighted and half wary, holds both possibilities, and the birds, of course, say nothing. Stevenson is best known for adventure novels such as *Treasure Island*, so a quiet lyric like this shows a different side of his writing. In a dozen simple lines it asks whether our deepest feelings belong to us or to the weather, and a reader is likely to go on turning that question over after the poem has finished.