It only stands to reason that where there's sacrifice, there's someone collecting the sacrificial offerings. Where there's service, there is someone being served. The man who speaks to you of sacrifice is speaking of slaves and masters, and intends to be the master.
When man learns to understand and control his own behavior as well as he is learning to understand and control the behavior of crop plants and domestic animals, he may be justified in believing that he has become civilized.
Man's unique reward, however, is that while animals survive by adjusting themselves to their background, man survives by adjusting his background to himself.
Ask yourself whether the dream of heaven and greatness should be waiting for us in our graves - or whether it should be ours here and now and on this earth.