Future generations will look back and identify a period during which, out of the histories of numerous peoples and societies—each rich and proud in its own right—a story of humanity in its entirety became discernible. We stand at the threshold of that transition today. Where past ages looked to the future through the lens of the family, the tribe, the city-state, or the sovereign nation, today we are not only able but impelled to take into account a shared future for all. This is the reality of the present moment, and ours is the opportunity and responsibility to choose how that future will be built and what values and priorities will characterize it.