§ Of Beren and Lúthien The Silmarillion

All that land was now become filled with evil, and all clean things were departing from it; and Beren was pressed so hard that at last he was forced to flee from Dorthonion. In time of winter and snow he forsook the land and grave of his father, and climbing into the high land of Doriath. There it was put into his heart that he would go down into the Hidden Kingdom, where no mortal foot had trodden. Terrible was his southward journey. Sheer were the precipices of Ered Gorgoroth, and beneath their feet were shadows that were laid before the rising of the Moon. Beyond lay the wilderness of Dungortheb, where the sorcery of Sauron and the power of Melian came together, and horror and madness walked. There spiders of the fell race of Ungoliant abode, spinning their unseen webs in which all living things were snared; and monsters wandered there that were born in the long dark before the Sun, hunting silently with many eyes. No food for Elves or Men was there in that haunted land, but death only. That journey is not accounted least among the great deeds of Beren, but he spoke of it to no one after, lest the horror return into his mind; and none know how he found a way, and so came by paths that no Man nor Elf else ever dared to tread to the borders of Doriath. And he passed through the mazes that Melian wove about the kingdom of Thingol, even as she had foretold; for a great doom lay upon him.