Perhaps only the agony of liberty lost could remind Americans why liberty is theirs by right. When I was a child, I stumbled upon philosophy through a tummy ache. I had eaten too much or run around too hard and found myself feeling miserable outside on a hot summer day. While I was in my own private agony, I remember thinking, "I'll never take all the hours I've spent without stomach pains for granted again." And I never did. Sometimes when other childhood problems had me down, I'd think, "Well, at least you don't have a stomachache," and I'd nod...