"The natural world is divided into countless species of living things-from plants to fish to birds to animals to humans."(Canadian society:1. The human species) There're various kinds of species on earth, all of them have several steps of development in their growth. Their development in appearance is easily can be seen, for instance, there length of body, difference in there shape of face, and etc. It's easy to find the physical development, however, it isn't really easy find to psychological development. Since, we just cannot study the psychology by doing biological experiment or observing the objects, many of psychologists had to do some researches on human in long term. Thanks to their achievements, nowadays, we know that how the mental stage is developed and details about each steps. Then, how the psychology of human is developed? We can get that answer by comparing two outstanding psychologists that...