Like all top predators, humans alternate between periods of feast and famine. Any time we see systematic waste of food resources during periods of famine, especially when such waste occurs in almost all cultures, we must assume the waste is only apparent and there is a reason for this waste. The key to understanding sacrifice is to remember that the primary advantage of humans versus other animals is a much larger brain and thus a much more complex and powerful mind. Sacrifice can be justified if it causes this powerful mind to function better, allowing more new food resources to be obtained than more than compensate for food resources wasted as part of the sacrifice.

The human mind is plastic, but not infinitely plastic. Anyone who has tried to stop smoking can confirm that willpower has its limits. One way to reshape the mind is to take advantage of the natural tendency towards consistency of thinking. For example, we give money to causes we believe in. By the principle of consistency, the logic also works in the reverse direction. By giving to a cause, we come to believe in that cause more strongly. Fund-raisers for charities and politicians take advantage of this principle, by encouraging very small donations initially, knowing that even a small donation will trigger a stronger attachment to the cause, leading to bigger donations down the road: "first they give, then they believe."

Gods are symbols or personifications of abstract principles. Sacrificing to a God causes the mind to focus on the principle represented by the God.