Domestic cats have two vocabularies; a vocabulary that they use in the wild and a vocabulary that they use in their relationship with human beings. In the wild cats are the adults and behave as such, but when they are domesticated they are the children and their behaviour reflects this. However, even when cats are domesticated they still retain their wild adult behaviour. This makes for a truly imposing vocabulary. Human beings appear to enjoy watching cats play and apparently they have done so for hundreds of years. They also find much pleasure in playing with them. In the days of the Roman Empire many great Romans were fascinated with the way cats played. Later many well known humans wrote expressively about cats' playful behaviour, although some were concerned that they might be considered to be frivolous. In the beginning of the human and dog relationship, the "dog" was almost certainly a wolf that simply became a domesticated wolf. This may be surprising because of the image of the big bad wolf that has been created in children's stories and other myths. This is a wildly distorted image that depicts the wolf as a savage and bloodthirsty creature and nothing like the friendly dogs that we are accustomed to today. The fact remains though that all modern breeds of dog, from Great Danes to Chihuahuas have evolved from the wolf in a very short genetic period and still retain its personality and behaviour patterns When it comes to domestication, horses were late-comers. They were first domesticated in the third millennium B.C., well after dogs, goats, sheep and cattle had entered the realm of the human being. The dog has always been considered to be the human being's best friend and it's quite safe to say that horses have always been considered to be the human being's best slave. The endless exploitation of horses is the result of their amazing willingness to cooperate with their human companions. By domesticating horses, the human being's ability to spread civilization was magnified dramatically. Up until the advent of the internal combustion engine, horses were the human being's main means of conquering the world. After this, the age of the horse waned dramatically, to be replaced by a growing respect and appreciation from their human companion.