The text states that in the end, 'only one’s own self remains.' How does this concept of self-reliance fit with the necessity of a Guru for spiritual progress?

This highlights a nuanced spiritual truth. Chapter 45 clarifies that worldly relationships with family like parents, sons, or a wife are ultimately unreliable for achieving the spiritual goal. Upon final reflection, only the self is the ultimate companion. However, the path to realizing this self is through the Guru. A seeker must give up hope in others and cultivate strong self-confidence. This self-reliance is then channeled into devotion to the Guru, who is identified as the 'true Brahman.' By renouncing the transient world and meditating solely on the Guru, the seeker uses their own effort, guided by the Guru, to achieve liberation.