In plain words
The master of all these senses is the Manas. The master of the Manas is the Buddhi. The master of the Buddhi is the jīva. The master of the jīva is God. Only when we join the senses to the Manas, unite the Manas with the Buddhi and join the Buddhi to the jīva do we understand this oneness of the jīva and Brahman. Of all the senses, the tongue is the mightiest. If we bring the tongue alone under control, all the senses come under control as well. This tongue: eating, and talking. When this tongue is joined to the Manas, these words come to a stop. From then on the Manas begins to talk. To stop the Manas from talking, we must rouse the Buddhi. When the Buddhi is awakened, it stops the talk of the Manas, and this Manas makes itself one with the Buddhi. When the senses join the Manas and the Manas the Buddhi, we must teach the Buddhi its lesson and make the effort to turn this Buddhi towards the jīva. Only when this Buddhi is turned towards the jīva does this jīva become one with Brahman. This is the right sādhana.
But, unable to recognise this orderly sādhana, man keeps developing his outward sight, all the time, for pleasures and riches, for his longings. Perhaps this is not their fault. All the senses face outward. The eyes face outward. The ears face outward. The mouth faces outward. The nose faces outward. Because all these senses face outward, man's nature keeps developing facing outward. Yet between the inner and the outer there is a bond in which neither is without the other. Man must try to recognise the bond, neither without the other, between the outer world and the inner world. What delights at the sight of beauty, what relishes food at the sight of it, what is enraptured at the sight of a fragrance: is it the body, or the Manas? When you inquire well, it is the Ātma that experiences all these, not the body. To experience this Ānanda of the Ātma is the chief duty of man.
The Ātma is the root of outward sight and the source of inner sight. What is this Ānanda of the Ātma? Revelling in every comfort, and making much of the body's strength and well-being, man goes on enjoying himself. That joy looks to man like the greatest Ānanda. But a hundred times greater than this joy is the Ānanda of the gandharvas. The Ānanda of the gods is a hundred times more blissful than this Ānanda of the gandharvas. The Ānanda of Devendra is a hundred times greater again than this Ānanda of the gods. A hundred times greater than this Ānanda of Devendra is the Ānanda of Indra.