The Xeroc PARC Principles divide tasks into two sets (copying is easy, creating is hard. There are more) based on the Nature of Human Beings: "What are human being like? They are impatient, have short memories, are slow, awkward, have limited logical abilities, get easily confused, like pictures better than words, are control freaks, vary considerably in their habits and preferences, lazy, make lots of mistakes even on easy tasks, are overly sensitive, can be easily made to feel guilty and inadequate, have limited imagination". Out of this come the idioms of the modern day graphical user interface.