Song
This poem is set to a song (“Non credo gia che pui infelice amanate”), as well as being about a nightingale’s song. It thus treats song as the medium for emotional expression. The nightingale “sings out her woes,” turning her pain into something beautiful: a book of songs. The speaker assumes that this release of emotion in the form of art helps to purify or cleanse the nightingale/Philomela of her pain: as she sings, the world around her goes from winter to spring.
The speaker argues that, while the nightingale is able to externalize her pain into song (her thorn is “without”), he is unable to do so. However, the very form of the poem belies this argument. “The Nightingale” itself is a sequence of two stanzas set to song, and thus has a music and cadence of its own. Furthermore, it repeats the same four-line refrain at the end of both stanzas, much like a song repeats it chorus. The speaker thus undercuts his own message, in fact expressing his pain in song, too.
Men's vs. Women's pain
The speaker compares a woman’s pain (Philomela’s) to a man’s (his own). In stating that the nightingale’s song is the expression of pain, he suggests that women are not only able to express their emotions—they are expected to. However, he casts doubt on the validity of women’s pain, stating that her only cause of pain is “Tereus’ love,” minimizing the anguish of rape. Furthermore, he calls her complaints “womanlike” in nature.
The speaker suggests that men’s pain, because it must be repressed, is worse than the pain that women suffer at the hands of men. In particular, the speaker states that the source of his pain is “craving” and “wanting” a woman’s love and touch. However, it is not socially sanctioned for him to speak of the pain of romantic and sexual longing—or of any pain. Although men are the stronger sex, capable of overcoming and harming women, they must suffer the “thorns” of their own pain internally.
Because the speaker believes male longing is more painful that a female’s rape, and because he minimizes Philomela’s pain, it may even seem that he suggests Tereus acted because of his repressed longing, thus excusing the harm of Tereus' actions. However, because the speaker does in fact express his pain in a song of his own (the poem), we may also interpret him to be a knowing hypocrite.