How long since you had to look inside a math book? Because here's a question that might have got by you: A down payment on a home costs $5,000. Housing one brain-damaged man for a year costs $20,000. How many families lose homes to mental retardation? This extra-credit teaser comes from a Nazi-endorsed schoolbook (currency adjusted). It was the first step in curing society of the unneeded. Shortly after, with the country now ready, beautiful killings ("euthanasia" in Latin) began. It is comforting to think that Nazis were demons rather than humans. But following their defeat you couldn't find an...