A handy short definition of almost all science fiction might read: realistic speculation about possible future events, based solidly on adequate knowledge of the real world, past and present, and on a thorough understanding of the nature and significance of the scientific method.
Robert A. HeinleinGirls are simply wonderful. Just to stand on a corner and watch them going past is delightful. They don't walk. At least not what we do when we walk. I don't know how to describe it, but it's much more complex and utterly delightful. They don't move just their feet; everything moves and in different directions . . . and all of it graceful.
Robert A. HeinleinThe right to figure things out for yourself is the only true freedom everyone shares. Go use it.
Robert A. Heinlein