In plain words
The jīva is the form of vyaṣṭi. God is the form of samaṣṭi. But the mind is the very form of these two, that is, of samaṣṭi and vyaṣṭi. Such sacred power the mind has had. But in this modern age they speak of the mind as the “monkey mind”. They say it is like a “mad monkey”. No, no: it is the symbol of sacred mankind. The mind came into being to make this mankind one with God.
So the mind is very sacred. “Mana eva manuṣyāṇāṃ kāraṇaṃ bandhamokṣayoḥ,” they say. It has been said that the mind is very powerful. Nothing else has the power the mind has. But the people of this world have not given the mind that much respect. They have not recognised the right meaning of this worldly, physical, natural word. The mind is very sharp. It is powerful. It is endowed with steadfastness, heroism, valour and purity. To recognise the nature of such a mind is very hard. If the mind itself were not there, the jīva and God would not appear to the world.
The whole essence of the Upaniṣads is in the one mahāvākya “Tat tvam asi”
As I said yesterday, the breath is the form of Īśvara, the mind the form of Viṣṇu, and speech the form of Brahmā. Nothing else has the power that speech has. Divinity, made up of the principles of Brahmā, Viṣṇu and Maheśvara, is this powerful. This power has been proved not in words alone but in the form of action too. Three words at a time came together and took shape as a mantra each, in the Vedas and in the Upaniṣads. To understand the essence of these Upaniṣads rightly is hard. “Tat tvam asi”, “Ayam ātmā brahma”, “Sarvaṃ khalvidaṃ brahma”, “Prajñānaṃ brahma”, “Brahmavit brahmaiva bhavati”: all these sayings of the Upaniṣads are great mantras. Every word is the very form of a mantra. These mantras too have many kinds of meaning. Of the four Vedas, the Ṛgveda, the Yajurveda, the Sāmaveda and the Atharvaveda, each Veda has one mantra (a mahāvākya) that makes known that Veda's essence.