The Nightingale

In "Ode to a Nightingale", the nightingale represents Keats' mortality. He loves it, because although it is mortality, it's song is immortal, which is exactly what he wants to become through song and story. But at the same time, he hates the nightingale, as it means that he will surely die, and there is no way of telling when or how, and if he will become immortal through song and poetry or not.