Their character is subjective and they constantly change. There are material sentiments, like thirst and hunger, and spiritual sentiments. There are also useful and harmful desires. Aristotle is the father of psychology. He calls psychology the history of the soul and he considers it as one of the most important sciences. He doe not agree with Plato that soul is independent, immaterial and supernatural. He believes that soul is a life giving power that is united with body. The body exists as long as soul provides it life. He tries to study the human soul in a scientific way. He agrees about the soul division in mentality, desire and sentimentality....
