The System of the Vedanta according to Badarayana's Brahma-Sutras and Cankara's Commentary c7.s5.t2.1

c7.s5.t2.1

When it is said: "This was Existent in the beginning" (above p. 230), the statement means that the world was already existent before its manifestation, in the form of the Existent, its cause. For where a thing is not already, according to its nature, it cannot arise: no oil can be pressed out of sand. But if the effect before manifestation was already identical with the cause, it remains so even after manifestation. As Brahman is never anything other than the Existent, so also the world is never anything other than the Existent. The Existent, however, is of like nature with itself (p. 459).