In plain words
…ham” (That am I): this is what it teaches. Why does man ignore this teaching from within and behave so foolishly? Who is doing all these works? The one who does and the one for whom it is done are one. One alone is the support of everything. Your words, your deeds, your hearing: all of them take place through the one God alone. So you are not doing service to someone else; you are doing it to yourselves. You must strive to grow this feeling of the one Ātma.
God is in you
‘Ahaṃ Brahmāsmi’, ‘Tat tvam asi’, ‘Prajñānaṃ Brahma’, ‘Ayam ātmā Brahma’: these four Mahāvākyas are the great teachings the four Vedas gave to the world. Why has man forgotten such words of the Veda? At every step his own reflection keeps appearing before him. In every breath divinity keeps shining. Instead of living his life mad for God, man behaves like a fool who knows nothing. He is not an ajñānī. He is a prajñānī, a sujñānī. You must recognise this truth. Before you eat, you pray, “Brahmārpaṇaṃ Brahma haviḥ.” But where is Brahman? He is in you. That is why the answer comes at once from within you. What does it say? “Ahaṃ vaiśvānaro bhūtvā prāṇināṃ deham āśritaḥ …” “O foolish man! I am right in your belly, in the form of Vaiśvānara”: this is the answer that comes. When you say “Brahmārpaṇaṃ …”, you are offering it to God, who is in your own belly. Whether you do good or harm, you do it to yourselves, not to others. For the divinity in all is one. “A salutation to any living being reaches Keśava”; “Contempt for any living being reaches Keśava.” Forgetting this principle of the one Ātma, you go round holy places and repeat the Name of God. Whatever name you call Him by, it is the one God who answers; whatever holy place you visit, it is the one God who is there. There, here, wherever you look, God is One alone. So do not divide the One into the many; keep in view the One that is in the many.