In the mid 2000s, Philadelphia real estate investor Zell Kravinsky found fame when he set out to donate his $45 million fortune, much of it to public health initiatives. After giving away all but $80,000, his family home and a minivan, Kravinsky donated a kidney—to a complete stranger—and later contemplated donating a second. To Kravinsky, a devout utilitarian, saving a life--any life--would be worth his. Who knows, he reasoned, what another person might be able to accomplis