Time, we know, is relative. You can travel light years through the stars and back, and if you do it at the speed of light then, when you return, you may have aged mere seconds while your twin brother or sister will have aged twenty, thirty, forty or however many years it is, depending on how far you traveled. This will come to you as a profound shock, particularly if you didn't know you had a twin brother or sister.
Douglas AdamsIt was none the less a perfectly ordinary horse, such as convergent evolution has produced in many of the places that life is to be found. They have always understood a great deal more than they let on. It is difficult to be sat on all day, every day, by some other creature, without forming an opinion about them.
Douglas Adams