Jewish tradition has it that someone always sits with the dead, that they are never left alone before burial. This is considered "high mitzvah" (mitzvah is a worthy deed) because that person can never come back to thank those who sat with them. That has always stuck with me, a charity more powerful because there is no possible way to acknowledge or repay it. It moved me to keep my charities towards the homeless anonymous but thinking it through, I see where it could cause a feeling of indebtedness with the recipient. Clearly, the x-ians who came up with this "grateful dead" thing have found a way around the need to repay!