§ Of Beren and Lúthien The Silmarillion

In that hour Lúthien came, and standing upon the bridge that led to Sauron's isle she sang a song that no walls of stone could hinder. Beren heard, and he thought that he dreamed; for the stars shone above him, and in the trees nightingales were singing. And in answer he sang a song of challenge that he had made in praise of the Seven Stars, the Sickle of the Valar that Varda hung above the North as a sign for the fall of Morgoth. Then all strength left him and he fell down into darkness.