Book excerpt: Don't worry -- the Kesslers know that parents aren't perfect. But they do believe that imperfect parents can raise their children on the foundation of a perfect system: the laws of nature, in particular the principle of causality -- that every action causes an equal and opposite reaction. The Kesslers show parents practical ways to teach their kids -- from infancy to young adulthood -- that negative actions cause negative results, and positive actions cause positive results, equipping them for happy and fulfilling lives at home and beyond. They also show parents how to avoid "the love ambush" -- the "you don't love me anymore" line used by children -- by letting their children know their role is not to receive love from them but to keep them safe.