In plain words
How can objects that change give the Supreme Principle that does not change? That is why the Vedas have been teaching many kinds of paths, so that this eternal Satya may be recognised.
The very first question the Veda put was this: inquire what causes such animal feelings and qualities to grow in man. Man is not born as man the moment he is born. Before this human state, he takes on many animal traits and animal births too, and at the very last enters this human birth. That is why, since these leftover animal traits are in us, these bad qualities spring up. If you look at someone, he lives on with a mind ever restless, without any steadiness at all. He makes many attempts to gain that steadiness. But steadiness does not come. Day by day this very restlessness keeps on growing. When the cause of this was inquired into, the Veda itself has been giving the right answer. Its answer is that because he once took shape in a monkey's birth, the traits of that monkey remain in him and have become the root cause of this restlessness. In the same way, if foolishness, or cowardice, or a thieving mind, or any other such evil traits appear in man, the root cause is this: one comes to understand that the remnants left over from such animal births of his in the past are the root cause of this behaviour. It lays down that offering such evil saṃskāras to God is the right remedy for this. This very quality of thieving keeps arising in many people. This thieving is the trait of the cat; restlessness is the trait of the monkey. Foolishness is the trait of the sheep; the quality called arrogance is the trait of the he-buffalo. In this way, following the saṃskāras of former births, their very natures turn into saṃskāras and keep being imprinted on man.
In yajña there are two kinds of yajña. One is the yajña related to the outer world; the second is the yajña related to the inner. For this outer yajña some altars, priests, samidhs and the materials fit for it are essential. People make offerings with these mantras and with cries of svāhā. They perform hōma. This is only a reflection of the yajña turned within. But no one inquires in the least into the inner yajña.