A river in Hades whose water causes the dead to forget their life on earth

Brief Analysis:
The speaker hears the nightingale's song and feels as if he had taken hemlock( a poisonous herb) or a drug such as opiate. He references moving towards the river of the underworld Lethe. This signifies his desire to forget his world on earth that is all too humane. He states that he is not jealous of the bird, but rather empathizes with and shares in the bird's happiness. He reveres the nightingale as he refers to it as a Dryad and its song as a "melodious plot"(8) to fill him with immense joy.