What is the meaning of the phrase "strikes a nail over the lines of destiny" as used in Chapter 10 of the Shri Sai Satcharitra?

In Chapter 10 of the Shri Sai Satcharitra, the phrase "strikes a nail over the lines of destiny" is a powerful metaphor for the Sadguru's ability to change a person's fate. The chapter explains that while all other gods might be illusory, the Guru is the one eternal God. Therefore, by placing complete and sincere faith in the Guru's feet, a devotee can have their predetermined destiny altered for the better. This highlights the supreme power of the Guru, who can intervene and override the course of one's life, untying the knot of birth and death and providing a path to liberation that transcends the otherwise fixed lines of fate.