A goodnight is meant to be a kindness, but Shelley's speaker hears one and flinches. The poem opens mid-farewell, with the words in quotation marks: "Buona notte, buona notte!" At once the speaker objects: "Come mai / La notte sarà buona senza te?" (How can the night be good without you?). Shelley, a poet best known for his English verse, wrote this one in Italian, and its idea is simple and sharp. The ritual phrase of parting cannot make a night good. Only being together can, and when the lovers are together the phrase is unnecessary.
The first stanza sets up this argument as a small paradox. "Non dirmi buona notte," the speaker pleads, "che tu sai, / La notte sa star buona da per sé." Night knows how to be good on its own. That sounds like a contradiction of the opening question, but the second stanza resolves it. The night is good for those who are together and bleak for those who are not. The phrase is either empty, because the night is already good, or cruel, because it announces that the night is about to turn bad.
The second stanza supplies the bleakness. "Solinga, scura, cupa, senza speme" piles up four descriptions with no connecting words, each heavier than the last. "Solinga" is a word for a person alone, and handing it to the night makes the darkness share the speaker's loneliness. The rhymes sharpen the contrast. "Speme" (hope) is answered by "insieme" (together), as though the poem were saying that hope simply is togetherness. "Abbandona" (abandons) is forced into rhyme with "buona," so the beloved's departure and the goodness of the night collide at the line ends. The image of hearts that "si battono insieme" gives the happy alternative a physical pulse, two heartbeats keeping time. Such lovers need no spoken blessing: "senza dirla, sarà buona."
The third stanza turns on sound. "Come male buona notte ci suona" puts "male" (badly) right beside "buona" (good), so the phrase seems to spoil in the mouth. Shelley then names what surrounds a goodbye: "sospiri e parole interrotte," sighs and broken words. The lover's farewell is a halting, half-choked thing, far from a smooth lullaby. The poem ends with a neat inversion: the way to have a good night is "mai non di dir la buona notte," never to say goodnight. A native ear might find the grammar of that last line a little strained. That is my inference, not a certainty, but the awkwardness suits a line about words failing.
The form fits the argument. There are three quatrains rhymed ABAB, and the lines run to about ten or eleven syllables, in the long, unhurried manner of Italian verse. The first stanza's rhymes (mai, te, sai, se) all fall on a stressed final syllable, which makes them crisp and clipped like a door closing. The later stanzas end on softer, trailing rhymes such as "buona," "abbandona" and "interrotte," so the poem seems to lose its firmness as the farewell sinks in. Repetition does the rest. "Buona" appears nine times in twelve lines, and "notte" is almost as constant. The poem says it distrusts the phrase "buona notte," yet it cannot stop saying it, and it ends on those very words. The speaker rejects the formula and is still held by it.
That irony is what makes the poem worth reading. It is a slight, quiet piece, but it takes up a very Romantic worry: that feeling is larger than the words made to carry it, and that ritual language can sound false at the moment it matters most. It also shows Shelley working in a second language and turning a commonplace phrase over until its sweetness goes sour. For a reader, the pleasure lies in watching a twelve-line argument close around two small words, which end up meaning almost the opposite of what they say.