True, our hearts are not in our hands. But our minds are: We can think about whatever we decide to think about. And therein lies our power. The mind rules over the heart—not just as a rider rules over his horse, but in a much more intimate sense. For the mind is the father and the mother, the seed and the womb from which the attitudes of a person are born and then nurtured. The heart does no more than reflect the state of the mind—its turmoil, its resolution, its shallowness or its depth, its coarseness or its maturity. This then must be the focus of the person who wishes to leave this world with...