Among many themes that are interconnected in "The Nightingale and the Rose", love is the universal topic. This main theme is explored through other -themes such as self-sacrifice and altruism. The theme of "love" is also analyzed through the essential questions: What is the true nature of it? and Is love real?
It is love that brings the Nightingale to the student, in the first place. Pining for the love of a young woman, the Oxford bachelor bemoans that there are no red roses in his garden, which is what the girl he loved requested in exchange for a dance.
The question of "What is the true nature of love?" comes into play because the Nightingale hears the student's complaints and feels that she (the Nightingale) can perhaps provide that token that the lovesick student wants. This is also the way self-sacrifice and altruism are included in the theme.
Be happy, cried the Nightingale, be happy; you shall have your red rose. I will build it out of music by moonlight, and stain it with my own heart's-blood.
Yet, the Nightingale makes a request: That the student becomes a "true" lover. By this, the bird is bringing forth her own ideas of what "true" love is. However, are these views also shared by the student?
All that I ask of you in return is that you will be a true lover, for Love is wiser than Philosophy, though she is wise, and mightier than Power, though he is mighty.
Clearly, the bird's own view of love is quite powerful. Powerful enough to stain a white rose with her blood in order to make it red. Still, when the ultimate sacrifice takes place, and the bird dies for it, the rose is ultimately rejected.
The girl thinks the student is beneath her, the student's ego becomes bruised, and he throws away the flower. This token of self-sacrifice and altruism in the name of "true" love is then ran over by a cart and is wasted away. This "true" love that the bird died for never existed in the first place.
Has the bird died in vain, or is there validity to her claim that there is such a thing as "true" love out there, even if it was not the case with the student? Those are the key questions prompted by the central theme of the story, and they are entirely open to interpretation as with much of Wilde's works.