So part of our challenge is reconciling these two seemingly inreconcilable truths -- that war is sometimes necessary, and war at some level is an expression of human folly. Concretely, we must direct our effort to the task that President Kennedy called for long ago. "Let us focus," he said, "on a more practical, more attainable peace, based not on a sudden revolution in human nature but on a gradual evolution in human institutions." A gradual evolution of human institutions.