From the perspective of the source material, what is the ultimate lesson imparted by the act of giving Udi?

The ultimate lesson imparted through the gift of Udi is the realization of the transient nature of the physical world and the importance of renouncing pride in our mortal bodies. Chapter 33 draws a powerful analogy, stating, "This worldly life is like Udi," and that our perishable bodies, like "water on a lotus leaf," will inevitably fall. The Udi, which is just ash or earth, represents the final destination of all name and form. By giving it, Baba was providing a constant, tangible reminder to contemplate the falsity of the material world and to use this understanding to realize the ultimate truth.