The idea of sympathy comes from very dubious origins in magic. It is the process whereby the pricking of an effigy can hurt the person that effigy is supposed to represent. If the magic works there thought to be a sympathy between the real person and the doll representing him. It is that similarity whereby dead objects take on a life of their own though the character they achieve by similarity to live objects. Anthropomorphism and biomorphism are examples of this kind of similarity.