“Now the long wait was ending. On yet another world, intelligence had been born and was escaping from its planetary cradle. An ancient experiment was about to reach its climax.
Those who had begun that experiment, so long ago, had not been men -- or even remotely human. But they were flesh and blood, and when they looked out across the deeps of space, they had felt awe, and wonder, and loneliness. As soon as they possessed the power, they set forth for the stars. In their explorations, they encountered life in many forms and watched the workings of evolution on a thousand worlds. they saw how often the first faint sparks of intelligence flickered and died in the cosmic night.
And because, in all the Galaxy, they had found nothing more precious than Mind, they encouraged its dawning everywhere. They became farmers in the fields of stars; they sowed, and sometimes they reaped.
And sometimes, dispassionately, they had to weed.”