"Now, although certainly such a bridle was foretold," the snake
conceded, a little uneasily, "how can I make sure that you speak the
truth when you say this particular bridle is Gleipnir?"

"Why, in this way: I will cast the bridle over your head, and then you
will see for yourself that the old prophecy will be fulfilled, and that
all power and all life will go out of you, and that the Northmen will
dream no more."

"No, do you keep that thing away from me, you little fool! No, no: we
will not test your truthfulness in that way. Instead, do you two
continue your ascent, to a more terrible destruction, and to face
barbaric dooms coming from the West. And do you give me the bridle to
demolish in place of you. And then, if I live forever I shall know that
this is indeed Gleipnir, and that you have spoken the truth."

So Niafer consented to this testing of his veracity, rather than permit
this snake to die, and the foundations of Norroway (in which kingdom,
Niafer confessed, he had an aunt then living) thus to be dissolved by
the loosening of the dying serpent's grip upon Middlegarth. The bridle
was yielded, and Niafer and Manuel went upward.

Manuel asked, "Snip, was that in truth the bridle called Gleipnir?"

"No, Manuel, it is an ordinary bridle. But this Serpent of the North has
no way of discovering this fact except by fitting the bridle over his
head: and this one thing the serpent will never do, because he knows
that then, if my bridle proved to be Gleipnir, all power and all life
would go out of him."