The Source

 1.4.14 Brahman is spoken of as the cause of all causes in all the Upanishads.

1.4.15 The visible world did not come from void or nothing, it came from Brahman, the Cosmic Energy Field that is invisible to human eyes.

1.4.16 Insentient prakriti cannot produce sentient beings, therefore, sentient Brahman is the cause of both sentient and insentient world.

1.4.17 see 1.1.31