In plain words
We need not learn all of them. We need not know them all. We need not recite them all. The essence of all these mahāvākyas lies in the one mantra “Tat tvam asi” alone. What does ‘asi’ mean? Joining: ‘tat’ and ‘tvam’; my joining with That: “Ahaṃ brahmāsmi”, I myself have been Brahman. I have joined Brahman. “Sarvaṃ khalvidaṃ brahma”: all of it is Brahman alone. All the meanings of these mantras teach nothing but one single meaning. Recognising such oneness is itself the true sādhana of these mantras. “Brahmavit brahmaiva bhavati”: one who has learnt That, who has known It, becomes Brahman itself. This is the right message of the Upaniṣads.
By the saṃskāra called God's grace, the jīva turns into God
Embodiments of Prema! Above all, you must know, “I myself am God.” Each one, in his own right, is an embodiment of God. “When each one is in his own right an embodiment of God, why should one worship God any more?”: this question arises. But you cannot recognise that the strength and the ability to worship God are within you. Being ordinary people, you are living an ordinary life in the worldly realm. How will those who lead such a life understand divinity? You are forms of vyaṣṭi. God is the form of samaṣṭi. How can vyaṣṭi recognise the form of samaṣṭi? Vyaṣṭi becomes the form of samaṣṭi only when it recognises the truth: I myself am the form of samaṣṭi. So you must recognise the truth, “I am God”. But how can you say this? For that you must fully develop the faith, I am God.
A potter went to the tank and brought back some clay. He heaped it in front of his house. On the second day he mixed water into the clay and made it into a lump. He put it on the wheel and shaped it like a pot. But pour water into that pot and it does not stay. Little by little it keeps seeping away. So you must put the clay pot in the fire, bake it, and give it the saṃskāra of fire. Only when you give it the saṃskāra of fire does the pot harden and the water poured into it stay.