§ Of Beren and Lúthien The Silmarillion

Huan it was that found Lúthien flying like a shadow surprised by the daylight under the trees, when Celegorm and Curufin rested a while near to the western eaves of Doriath; for nothing could escape the sight and scent of Huan, nor could any enchantment stay him, and he slept not, neither by night nor day. He brought her to Celegorm, and Lúthien, learning that he was a prince of the Noldor and a foe of Morgoth, was glad; and she declared herself, casting aside her cloak. So great was her sudden beauty revealed beneath the sun that Celegorm became enamoured of her; but he spoke her fair, and promised that she would find help in her need, if she returned with him now to Nargothrond. By no sign did he reveal that he knew already of Beren and the quest, of which she told, nor that it was a matter which touched him near.