Can you explain the metaphor of Sai's life being a 'vast ocean' and the author being a 'Titwi bird'?

In Chapter 2, this metaphor is used to justify the creation of a new book despite many existing ones. Sai's life is described as a 'vast ocean, an infinite mine of jewels,' which signifies that his story is boundless, deep, and impossible to capture in its entirety. The author compares themself to a 'Titwi bird trying to empty it,' a creature far too small for such a monumental task. This highlights the author's humility and acknowledges that no single book can ever fully encompass the depth of Sai's life. The metaphor serves to explain that any attempt to tell his stories, no matter how small, is a worthy endeavor, and one should find satisfaction in whatever portion can be shared.