THE TWO SURVIVING Founders of Zion were old men, old with the accelerated aging that overtakes men who spend too many years outside the embrace of gravity. Their brown legs, brittle with calcium loss, looked fragile in the harsh glare of reflected sunlight. They floated in the center of a painted jungle of rainbow foliage, a lurid communal mural that completely covered the hull of the spherical chamber. The air was thick with resinous smoke.