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

The analogy of the stone and the gem, as presented in Chapter 19, illustrates the role of a disciple's inherent nature in the process of spiritual development. Both a stone and a gem can be rubbed on a whetstone, which represents the Guru's guidance and polishing process. While the process is the same for both, the outcome is vastly different: the gem 'becomes a brilliant jewel,' while the stone merely 'remains smooth by its own nature.' This metaphor suggests that while a Guru's teachings are essential, the disciple must possess the innate qualities of a 'gem'—such as the capacity for strong faith and patience—to truly transform and attain spiritual brilliance. The Guru's efforts are most fruitful with a disciple who is receptive and has the inherent potential for transformation.