Quote 10
It was an old song, old as the breed itself--one of the first songs of the younger world in a day when songs were sad. It was invested with the woe of unnumbered generations, this plaint by which Buck was so strangely stirred. When he moaned and sobbed, it was with the pain of living that was of old the pain of his wild fathers, and the fear and mystery of the cold and dark that was to them fear and mystery. And that he should be stirred by it marked the completeness with which he harked back through the ages of fire and roof to the raw beginnings of life in the howling ages. (3.28)
Buck finds camaraderie in the past generations of dogs like himself because they have all suffered similar hardships in the wild.
Quote 11
All that stirring of old instincts which at stated periods drives men out from the sounding cities to forest and plain to kill things by chemically propelled leaden pellets, the blood lust, the joy to kill--all this was Buck's, only it was infinitely more intimate. (3.33)
Buck finds a connection to his past when he experiences killing.
Quote 12
There is an ecstasy that marks the summit of life, and beyond which life cannot rise. And such is the paradox of living, this ecstasy comes when one is most alive, and it comes as a complete forgetfulness that one is alive. This ecstasy, this forgetfulness of living, comes to the artist, caught up and out of himself in a sheet of flame; it comes to the soldier, war-mad on a stricken field and refusing quarter; and it came to Buck, leading the pack, sounding the old wolf-cry, straining after the food that was alive and that fled swiftly before him through the moonlight. He was sounding the deeps of his nature, and of the parts of his nature that were deeper than he, going back into the womb of Time. He was mastered by the sheer surging of life, the tidal wave of being, the perfect joy of each separate muscle, joint, and sinew in that it was everything that was not death, that it was aglow and rampant, expressing itself in movement, flying exultantly under the stars and over the face of dead matter that did not move. (3.34)
Buck experiences joys and emotions in the frozen North that never would have been possible back in the Santa Clara Valley. Despite the hardships he suffers, there is an "ecstasy" involved in connecting with his primitivity.