In plain words
Students! In these five days we have learned something about the body, the senses and the Manas. But only when you recognise matters of this kind will it become clear to you what life is. First we must learn about the Buddhi. This is what matters most. When there is water in the tank, you can let it out through the tap. So the body, the Manas and the senses are all the taps, but the Buddhi is the tank. Whatever water we fill into this tank, that same water comes out of the taps. It is on this basis that Vedānta said: yad bhāvaṃ tad bhavati. So let us talk further about this tank, which is the foundation of all of them.