This composition was inspired by the timeless ancient Greek myth of Orpheus and Eurydice:
"Eurydice and Orpheus were young and in love. So deep was their love that they were practically inseparable. So dependent was their love that each felt they could not live without the other. These young lovers were very happy and spent their time frolicking through the meadows. One day Eurydice was gaily running through a meadow with Orpheus when she was bitten by a serpent. The poison of the sting killed her and she descended to Hades immediately.
Orpheus was son of the great Olympian god Apollo. In many ways Apollo was the god of music and Orpheus was blessed with musical talents. Orpheus was so sad about the loss of his love that he composed music to express the terrible emptiness which pervaded his every breath and movement. He was so desperate and found so little else meaningful, that he decided address Hades. As the overseer of the underworld, Hades heart had to be hard as steel, and so it was. Many approached Hades to beg for loved ones back and as many times were refused. But Orpheus' music was so sweet and so moving that it softened the steel hearted heart of Hades himself. Hades gave permission to Orpheus to bring Eurydice back to the surface of the earth to enjoy the light of day. There was only one condition--Orpheus was not to look back as he ascended. He was to trust that Eurydice was immediately behind him. It was a long way back up and just as Orpheus had almost finished that last part of the trek, he looked behind him to make sure Eurydice was still with him. At that very moment, she was snatched back because he did not trust that she was there. When you hear music which mourns lost love, it is Orpheus' spirit who guides the hand of the musicians who play it."
Taken from Thomas Bulfinch and retold by Juliana Podd in Encyclopedia Mythica