The sacrifices, you will have seen, are of the utmost importance to our Vedic religion. The Lord himself has spoken about them in the Gita. When Brahma created the human species he also brought the yajnas or sacrifices into existence, bidding mortals thus: "Keep performing sacrifices. You will obtain all good fortune. May these sacrifices of yours be the cow (Kamadhenu) that grants you all you desire"
Saha-yajnah prajah srstva puro'vaca Prajapatih
Anena prasavisyadhvam esa vo'stvista-kamadhuk
If we assume that Brahma "created humans and with them sacrifices", it is likely to be construed that he first created human beings and then sacrifices. But actually it is stated in the Gita that Prajapati created yajna along with humankind (saha-yajnah prajah srstva). Yajna is mentioned first and then praja (mankind).
Since the mantras of the Vedas are the source of creation, the vibrations produced by chanting them will bring the divine powers invested with the authority of performing certain functions. To recite such mantras at a sacrifice is like writing the address on an envelope. It is by performing homa in this way that the oblation is conveyed to the deity invoked by Agni.
The dog is stronger than the cat, the horse stronger than the dog, the elephant stronger than the horse, and the lion stronger than the elephant. To extend this sequence, who are stronger than men? The devas, or celestials. While in this world they remain dissolved in the five elements, in the celestial world they exist in a visible form. Those who have obtained siddhi or perfection by chanting the mantras can also see them in their gross form in their celestial abode besides receiving their blessings in their subtle form. The gods emanated from the Paramatman as a result of the vibrations produced by the mantras. We may therefore describe the mantras as the "sonic" form of the deities.
The deity appears during a sacrifice when he is invoked with mantras. Those who are wise and mature will perceive them with their eyes. Even if they do not, the power of the deities will be subtly revealed to them. However, offerings cannot be made directly to them. When you write a letter you have to stick a stamp on it or put the seal of the registrar. According to the "regulations" of the Vedas, any oblation intended for the celestials must be offered in the sacred fire in a form acceptable to them.
What remains after the sacrificial fire has consumed the offering ("yajnasista") is taken as prasada by the performers of the sacrifice. The question is asked: how does the same reach the deities invoked? We should not entertain such doubts. The deities are not like us created of the five elements. So they do not require food in the gross form. Even in our case the food we eat is burned (digested) by the gastric fire. Its essence alone is conveyed to all parts of the body in the form of blood. The subtle essence of the offerings are conveyed by the sacrificial fire to the deities invoked.
You know how a toast is proposed to the guest of honour at a dinner or banquet. The host and invitees drink to his health. This means that, when a group of people drink or eat ceremonially, the benefit goes to someone else. Do you ask how this is possible? Such things can be explained only on the basis of a certain mental attitude. Good intentions and good thoughts have their own creative power.
When the thought waves of the Paramatman have come to us in the form of mantras, they must truly be pregnant with the utmost power for good. The offerings made to the deities with the chanting of mantras will increase their strength. The celestials are of course strong but they are neither almighty nor full. They too have their wants and desires and these are met by the sacrifices performed by us. If they help us by making our mundane existence happier we have to help them by performing sacrifices. If we conduct yajnas so that they may flourish, they will in return bless us with well-being. Sri Krsna says in the Gita:
Devan bhavayata'nena te deva bhavayantu vah
Parasparam bhavayantah sreyah param avapsyatha
Our religious texts are replete with accounts of how people have merited the grace of Isvara and pleased the celestials by performing sacrifices.
If the celestials bring us rains, bless us with food, health, etc, why should we perform sacrifices so as to provide them with food, we are asked. " Why should we feed the deities when we ourselves are dependent on them for our food and clothing? Why cannot they manage to obtain food on their own? How would you explain the Lord's statement (in the verse quoted above), 'Parasparam bhavayantah'? To say that we must regard the celestials as great beings and make obeisance to them seems reasonable enough. So let us worship them. But, instead of this, why are we seemingly elevated and placed on an equal footing with them? What is the meaning of our being told: 'You sustain them and let them sustain you - you feed them by performing sacrifices and let them bless you with rains'? "
When I consider such questions, it seems to me that the world of the celestials is like England and that they themselves are like Englishmen. Is there much agricultural land in England? No. Yet Englishmen lorded it over the world. They boasted: "The sun never sets on our empire. " What was the secret of their world dominance?
England is poor in food resources. It has plenty of coal and chalk - coal that is black and chalk that is white. These are the main resources of Englishmen but they cannot eat them. If machines and factories are to be installed in countries where food crops are grown in plenty, they will need a lot of coal and chalk. That coal is essential to industry is well known. (Petrol and electricity came later. Now there is atomic power also. ) For some industries like cement, chalk (limestone) is essential.
Englishmen thought up a shrewd plan. They induced other countries to start factories using machinery and fomented new, unnecessary desires among people there. And they sold lumps of coal and chalk to these countries and got in return foodgrains, cotton, etc, in abundance. In this way they brought country after country under their heel.
There are no agricultural lands in the celestial world. The vedas have no means to feed themselves. "Durbhiksam devalokesu manunam udakam grhe", so it is said in the first prasna (first part) of the Taittiriya Aranyaka. Rain is produced when the clouds precipitate. It is only on earth that rain can be made use of - it fills the rivers, lakes and wells. The celestials have to come to our households for water. On earth alone there is plenty because of cultivation carried on by irrigating the fields. There is famine in the celestial world since it has no agricultural land: this is the meaning of the words quoted from the Aranyaka.
However, we need the grace of the gods if we are to be blessed with rains. To deserve such grace we must perform sacrifices. Otherwise there will be no rains on earth. The result will be famine or the rain will fall into the sea and not on land, or it will be either ativrsti (too much rain) or anavrsti (no rain). We have to depend on the denizens of the celestial world to send us the right quantity of rain to create abundance on this planet.
Just as England has plenty of coal but does not have sufficient agricultural land, the celestials have an abundance of grace but no crops to grow - they cannot also sustain themselves with their power of grace. Because they send us rain we are able to raise crops and sustain ourselves. For our part we can enhance their power of grace by chanting the Vedas. The oblations offered in the sacrificial fire with such chanting become their nourishment.
Our country grows cotton. When our spinning mills did not prosper, the English took our cotton to Lancashire, made "nice" cloth and sold it to us, making in the process four times profit. The celestials produce rain for us from the water vapour formed from our own seas. But, unlike the English, they do not make any profit out of it (in the transaction). In fact the blessings they give us are far more than the sustenance we give them. As I said earlier, the celestials are much stronger than we are. The Lord has assigned us the duty of performing various rites and the celestials have to find satisfaction in them. By doing so, it seems, he has raised us to the level of the celestials. "Parasparam bhavayantah" he says in the Gita. The gods and mortals support each other.
For a general background, please see here