It all comes down to a small, secretive, solitary songbird that goes on singing late into the night. It begins - and ends, too - with an unseen bird that continues to trill and whistle in the darkness long after the other birds have quieted for the evening. Its voice breaks the stillness. The nightingale is a common Old World bird with an uncommon sound: rich, loud, mellow, melodious. It has stamina and sings with an eerie natural beauty that reverberates like a chord through European and Asian poetry. Its song is strong and fitful - restless, compelling. It crescendoes.

The nightingale has always had tremendous metaphorical and symbolic power. It seems to fill a need - apparently irresistible - to attribute human feeling to the bird's pure and persistent song. Poets, who are often nocturnal creatures, have especially identified with 'spring's messenger, the sweet-voiced nightingale', as Sappho calls it. They have also noted its difference from us. The nightingale sings during the day as well as the night, but poets have especially praised its night music, it mournful tones and its joyous sound.

In his magisterial defence of poetry, Shelley establishes the connection between the poet and the nightingale. He writes:

A poet is a nightingale, who sits in darkness and sings to cheer its own solitude with sweet sounds; his auditors are as men entranced by the melody of an unseen musician, who feel that they are moved and softened, yet ...