The line describes Buck’s relationship with John Thornton, presenting it as the first bond he experiences as genuine, passionate love. Earlier in his life, Buck had known comfort, familiarity and forms of loyalty towards people, but London distinguishes those attachments from the intensity of his feeling for Thornton. The statement marks an important change in Buck’s emotional life, showing that his experiences in the North have not removed his capacity for affection.

Within the novel, this love is expressed through loyalty, trust and a strong desire to remain close to Thornton. Their relationship contrasts with the cruelty and exploitation Buck has experienced from other people. At the same time, Buck continues to feel the pull of the wilderness, creating a tension between his attachment to Thornton and his growing instinct for an independent life. The quotation therefore captures both the depth of their bond and its importance in Buck’s development.