What is the primary teaching about Udi (sacred ash) that Sai Baba conveyed, as detailed in Chapter 33?

According to Chapter 33 of the Shri Sai Satcharita, the Udi given by Sai Baba carries a profound spiritual teaching. The chapter explains that Baba used the sacred ash to illustrate the transient nature of the physical world. The core message is that the entire visible universe is ultimately impermanent, just like ash. Baba intended for devotees to remember that the body, made of five elements, is temporary and will also turn to ash once its destined experiences are exhausted. As mentioned in Chapter 33, this practice served as a constant reminder that Brahman alone is the ultimate reality, while the cosmos is an illusion (Maya).