In plain words
To remember the Divinity within oneself, to build one's own mind into the altar of yajña, and to sacrifice in it the evil qualities left over there: that is the inner meaning of yajña. That is why these yajñas came into being: so that we might change our evil qualities, evil nature and evil conduct, and make our divine humanness shine forth. Restlessness is not man's nature. Anger is not man's nature. Thieving too is not man's nature. Still less is foolishness man's nature. If man experiences all these bad qualities which are not his nature, the root cause is the fruit of the saṃskāras of former births. So the tyāga we must make is this: we must give up these bad qualities that fill us, that torment us and that make us forget our humanness.
Here is a fine example of this. Within us there is a kind of āśrama. What is this āśrama? What removes śrama, weariness, is the āśrama. What protects those who take refuge is the āśrama. What brings shelter is the āśrama. What fulfils our wishes is the āśrama. But this is no ordinary āśrama. The place from which the awareness "I, I" springs forth: that is what they called the āśrama. This āśrama, which makes every wish come true, they have called the Siddhāśrama. The story goes that Viśvāmitra lived in this Siddhāśrama. Who is this Viśvāmitra? Only a person? A muni? Or a ṛṣi? No, no. When a man turns the power of awareness within him towards the Lord, he himself becomes Viśvāmitra. He makes the effort to perform the yajña that turns such a vision of his towards Divinity. To protect this yajña he prays to Rāmacandra. Who is that Rāma? He is not just the form of an individual. He is the One whose nature it is to delight the Ātma itself. That is why He bears the title Ātmārāma. Viśvāmitra has the faith that when he takes refuge in this Ātma, his yajña will be fulfilled. So, because that vision is turned towards Divinity, Rāma appears there. Appearing there, He slays Mārīca and Tāṭaki. Who are these, Mārīca and Tāṭaki? They are attachment and hatred. On the day these, attachment and hatred, are slain, on that very day Viśvāmitra's yāga is complete. So everything lies within man himself.
Man's speech itself is the Ṛg Veda. The mind itself is the Yajur Veda. The prāṇa itself is the Sāma Veda. The oneness of the three is itself the divine Ātma-tattva. So the Ṛg, Yajur and Sāma Vedas are all simply humanness that has taken on a form.