Can you explain the connection between the Dhuni, the firewood, and the Udi as described in Sai Satcharitra?

Chapter 33 of the Shri Sai Satcharitra details a clear process connecting the Dhuni, firewood, and Udi. Baba would regularly purchase bundles of firewood and offer these logs into the sacred Dhuni, a fire he kept constantly burning in the Masjid. The ash that remained from these burnt logs was the Udi, or sacred ash, which he would then distribute. This chapter explains that this was not just a ritual but a teaching. The Udi produced from the wood in the fire served as a potent symbol for the impermanence of the physical world, including our own bodies, which are likened to wood that will eventually turn to ash.