ters since he
had come into the Northland had bred in him a fear that no master could
be permanent. He was afraid that Thornton would pass out of his life as
Perrault and Francois and the Scotch half-breed had passed out. Even in
the night, in his dreams, he was haunted by this fear. At such times
he would shake off sleep and creep through the chill to the flap of
the tent, where he would stand and listen to the sound of his master's
breathing.

But in spite of this great love he bore John Thornton, which seemed
to bespeak the soft civilizing influence, the strain of the primitive,
which the Northland had aroused in him, remained alive and active.
Faithfulness and devotion, things born of fire and roof, were his; yet
he retained his wildness and wiliness. He was a thing of the wild, come
in from the wild to sit by John Thornton's fire, rather than a dog
of the soft Southland stamped with the marks of generations of
civilization. Because of his very great love, he could not steal from
this man, but from any other man, in any other camp, he did not hesitate
an instant; while the cunning with which he stole enabled him to escape
detection.

His face and body were scored by the teeth of many dogs, and he
fought as fiercely as ever and more shrewdly. Skeet and Nig were too
good-natured for quarrelling,--besides, they belonged to John Thornton;
but the strange dog, no matter what the breed or valor, swiftly
acknowledged Buck's supremacy or found himself struggling for life with
a terrible antagonist. And Buck was merciless. He had learned well the
law of club and fang, and he never forewent an advantage or drew back
from a foe he had started on the way to Death. He had lessoned from
Spitz, and from the chief fighting dogs of the police and mail, and knew
there was no middle course. He must master or be mastered; while to show
mercy was a weakness. Mercy did not exist in the primordial life. It was
misunderstood for fear, and such misunderstandings made for death. Kill
or be killed, eat or be eaten, was the law; and this mandate, down out
of the depths of Time, he obeyed.

He was older than the days he had seen and the breaths he had drawn. He
linked the past with the present, and the eternity behind him throbbed
through him in a mighty rhythm to which he swayed as the tides and
seasons swayed. He sat by John Thornton's fire, a broad-breasted dog,
white-fanged and long-furred; but behind him were the shades of all
manner o