Lay of Leithian Canto IV
From Tolkien Gateway
This Canto first speaks of Beren “He lay upon the leafy mould/his face upon earth’s bosom cold/aswoon with overwhelming bliss/enchanted of an elven kiss”. Then it tells of Lúthien’s return and their dance, and how Dairon espied them, and as he loved Lúthien he betrayed them to Thingol. Then how Lúthien led Beren into Menegroth after Thingol promised her that his life would be spared. There he requested the hand of Lúthien, and Thingol, as he was bound to his oath not to harm Beren, in his wrath gave the bride-price as a Silmaril. Then Beren laughed as if it were a small thing, and left the hall with the promise to bring one back. This fourth canto can be considered the true beginning of the quest.