The voice i hear this passing night was heard
in ancient days by emperor and clown:
perhaps the selfsame song that found a path
through the sad heart of ruth, when, sick for home,
she stood in tears amid the alien corn;

what is the main idea of these lines from verse ii of “ode to a nightingale” by john keats?

a. the bird’s song is like mortals; it will die.
b. the bird’s song has been heard throughout the ages.
c. ruth is crying because she cannot hear the bird’s song.
d. the voice the speaker is hearing is not actually the bird singing but his own thoughts.