First. Argumentation and reliability of texts
In the sutra of the Naga king's questions, it is said:"The great treasury of the indestructible bodies of the three Jewels is inexhaustible, the great treasury of the boundless great understanding of the Teaching is inexhaustible, the great treasury that satisfies living beings is inexhaustible, the great treasury that is equal to the heavenly space is inexhaustible, the great treasury that is represented by these four is inexhaustible." So it is said about the own nature or essence of the treasury.