How is knowing Brahman equal to knowing everything?

[A devotee asked through Śrī Anil: What is meant by the statement of the Upaniṣads “By knowing that (Brahman), everything is known?” Does that mean that we become omniscient after self-realisation and we come to know all the sciences, arts, religions, etc?]

Swāmi replied: When you know that the entire pot ware is made of clay, you will know that everything is essentially clay. “Everything is known” means that the causal material of everything is known. All the things in the world are made of energy alone. Hence, you will know that the entire world is nothing but an appearance or modification of energy. You will know that the entire world basically is energy. Going a step further, even this energy is created by God. All the modifications of the energy are also created by God and not by the inert energy. Hence, when it is said that everything is known, it means that you will come to know that everything has been created by God alone. As such you, as a soul, can never get the entire knowledge of everything created by God. Only God has the entire knowledge of everything and He alone is omniscient.