When we discern things we classify them in various groups or categories. I see a horse, then I see another horse, and another. The horses are not exactly alike, but they have something in common, and this common something is the horse's "form"....So we go around pigeonholing everything. We put cows in cowsheds, horses in stables, pigs in pigsties, and chickens in chicken coops. The same thing happens when Sophie Amundsen tidies up her room. She puts her books on the bookshelf, her school books in her schoolbag, and her magazines in the drawer. Then she folds her clothes neatly and puts them in the closet - underwear on one shelf, sweaters on another, and socks in a drawer on their own. Notice we do the same thing in our minds....The day that you find something you are unable to classify you will get a shock. If for example, you discover a small whatsit, and you can't really say whether it is animal, vegetable, or mineral - I don't think you would dare touch it.

+Jostein Gaarder, Sophie's World