If something it’s impossible via a linear and frontal way, tradition found a way to get it is the sacrifice. You need to give something, to get something at a low level. At a high level, you need to sacrifice something. The notion of sacrifice is something like a proof of your devotion. The sacrifice has evolved into an offering. With Time tradition has evolved itself. And the offering oblations and libations into sacred fire became a symbolic offering in the presence of sacred fire. This is a way to reserve, to respect, to be devoted. In some traditions the intercourse was laterally considered as symbolically equivalent to the sacrifice and ejaculation of semen as the offering.