According to the text, what was the primary spiritual lesson Baba intended to convey through the constant burning of the Dhuni and the giving of its ash?

The primary spiritual lesson Baba conveyed through the Dhuni and its Udi was the distinction between the transient material world and eternal spiritual truth. Chapter 33 of the Shri Sai Satcharita poses the question of the significance of this ritual and provides a clear answer. The Udi demonstrates that the entire visible universe is ephemeral, destined to become ash. Baba used it to remind everyone, including himself, that our physical bodies are also temporary. The core message, as stated in the text, is that "Brahman alone is real, the cosmos is infinite," and the Udi is a tangible sign of this truth, helping one to look beyond the veil of Maya.