Mars was empty before we came. That's not to say that nothing had ever happened. The planet had accreted, melted, roiled and cooled, leaving a surface scarred by enormous geological features: craters, canyons, volcanoes. But all of that happened in mineral unconsciousness, and unobserved. There were no witnesses--except for us, looking from the planet next door, and that only in the last moment of its long history. We are all the consciousness that Mars has ever had. -Kim Stanley Robinson