Can you explain the analogy of the stone and the gem in the context of a Guru's guidance?

The analogy of the stone and the gem, found in Chapter 19, illustrates the role of a disciple's inherent nature in the process of spiritual development. The text explains that both a stone and a gem can be polished on the same whetstone, which represents the Guru's teachings and guidance. However, the outcome is different: 'the stone remains a stone, but the gem becomes a brilliant jewel.' This suggests that while the Guru provides the same opportunity for refinement to all, the disciple's inner quality, or readiness, determines the result. The passage implies that a Guru expects more than just presence; he looks for 'the disciple's wisdom' and the virtues of faith and patience to truly transform, much like a gem's inherent quality allows it to become brilliant when polished.