Think of our world as it looks from the rocket that is heading toward Mars. The water of the rivulet was dark with endless drift and mirrored the high-drifting clouds. "Do?" I echoed so loud that Miles and Flora, as they passed at their distance, paused an instant in their walk and looked at us. I used to wonder how my little charges could help guessing that I thought strange things about them; and the circumstances that these things only made them more interesting was not by itself a direct aid to keeping them in the dark.