For all its progress and possibilities, our modern world has difficulty seeing beyond itself. Every age has to struggle against its blind spots. In ancient Rome, for example, the span of a person’s influence was reckoned at 100 years. Within that horizon individuals could remember two generations back and care for two generations forward. Then, as the custom went, that influence stopped, and a new century, with new people and new concerns, would reset itself.[2] But lasting societies need a broader vision.
