The idea of purpose in one’s life is clearly a major theme in the novel as it appears in the title, A Dog’s Purpose. From his very first moments, the dog who is known by many names, but who we’ll call Bailey, understands that there must be a purpose to his existence. In his first life, purpose is difficult for him to understand because his life is short and tragic. Yet, he comes to understand that humans play a significant role in a dog’s life. His first clear understanding of this is illustrated when he says, “[M]y life would be what he decided it would be” (62). Bailey comes to this conclusion when a man picks him up off the side of the road at the beginning of his second life, and Bailey offers unbridled trust, unaware that the man is about to leave him to die of heat exhaustion in a locked truck. This reliance on humans, for better or for worse, is the first lesson Bailey learns in his search for purpose.

Over the course of his second life, the first life in which Bailey lives to adulthood, he learns many lessons, most of which center on the role of a dog as a pet.