Sacrifice means to please the Supreme Lord. krishna

vasudeve bhagavati
bhakti-yogah prayojitah
janayaty asu vairagyam
jnanam ca yad ahaitukam
[SB 1.2.7]

Just, for example, that we are eating. Eating is necessary. So long my body is there, eating is necessary. So in the Bhagavad-gita it says,

yajnarthat karmano 'nyatra
loko 'yam karma-bandhanah
yajna-sistasinah santo
mucyante sarva-kilbisaih
[Bg. 3.9]

that one who performs sacrifice... Sacrifice means to please the Supreme Lord. That is the sacrifice, meaning of sacrifice. Otherwise sacrifice has no meaning. Sacrifice means... Suppose you have got one thousand dollars in your pocket. Now you sacrifice it. You spend it for some good cause. "Oh, this man has sacrificed one hundred dollars." But that sort of sacrifice is also cause of your bondage. Now, suppose you have given to a poor man one hundred dollars to help. Now, the, according to law of karma, you have given one hundred dollars to a poor man to help him. This means that the poor man has to pay you four hundred dollars in your next life, with interest and compound interest. And you will have to take that four hundred dollars. And suppose you are preparing yourself to conquer over the next life, but by contributing this one hundred dollars you are now bound up to take payment of four hundred dollars; therefore you have to take your birth. These are subtle laws. If we are to believe the Vedic literature, the law of karma, these are stated there. We may take it or not take it. That is a different thing. Just like if you deposit in the bank one hundred dollars. So if you forget, twenty years after you will have to take two hundred dollars. The bank will pay you, either you like to take it or not take it. Just like we have this law in this ordinary life, similarly, anything, good action or bad action, we have to suffer or enjoy the result. That is called reaction. But sacrifice for the cause of the Supreme Lord, that has no reaction. This is also bright side. There are so many wrong side also.

So Bhagavad-gita says that yajna-sistasinah santo mucyante sarva-kilbisaih. Sarva-kilbisaih. Sarva-kilbisaih. Kilbisa means sinful reaction, sinful reaction, "Tit for tat," good reaction or bad reaction. But one who eats after offering to the Supreme Lord, he is not under the regulation of reaction. Whatever we eat... Even we eat, that, we have got to repay for that. Now, the Sanskrit word, the flesh... Flesh, Sanskrit word, is called mamsa. Mamsa. The mamsa means..., mam means "me," and sa means "he." "So I am eating some animal; so in my next life that animal will eat me." That is called mamsa. So now, apart from animal... Don't think that those who are vegetarian, they are free from all these reaction. No. They are also. They are also. The law is that one has to repay which he is taking the help from other living entities. That is the law of karma. So either you eat vegetables or either you eat flesh, you have to repay that. But yajna-sistasinah santo mucyante sarva-kilbisaih. The Bhagavad-gita says that if you eat the remnants after offering sacrifice to the Lord, then you, not only you are free from all reaction, but you do not eat anything sinful. That is the direction of Bhagavad-gita.

So in every aspect of our life... This is also one of the insignificant example of our activities of our life. If we act, dovetailing our actions with the Supreme Lord, then we are free from reaction. Otherwise we are bound up by the reaction. That is the law. So in order to get myself free from all reaction of my activities.. . Because so long I am... Because I am living entity, I have to act. Either I act spiritually, either act materially, I have to act. My activities will not stop. It is foolishness to say that "I will stop my activities." No. That cannot be. Your activities will go on. If you don't act spiritually, then you have to act materially. And if you are fully engaged in spiritual activity, then there is no chance of material activity. Because after all, you are actor, one, if you are engaged in something. Just like in our ordinary life, if we do something at a particular moment, we cannot do other things; similarly, we have to engage ourselves fully in the spiritual life. Then our material activities will be stopped altogether, and then there will be no reaction. In spite of our acting... Just like the soldier. In spite of his killing hundreds and thousands of people, he is not to be hanged; he is to be rewarded. This is the technique.