Aristotle
Aristotle (384 BC – 322 BC) posited an ethical system that may be termed "self-realizationism." In Aristotle's view, when a person acts in accordance with his nature and realizes his full potential, he will do good and be content. At birth, a baby is not a person, but a potential person. In order to become a "real" person, the child's inherent potential must be realized. Unhappiness and frustration are caused by the unrealized potential of a person, leading to failed goals and a poor life. Aristotle said, "Nature does nothing in vain." Therefore, it is imperative for persons to act in accordance with their nature and develop their latent talents, in order to be content and complete. Happiness was held to be the ultimate goal. All other things, such as civic life or wealth, are merely means to the end. Self-realization, the awareness of one's nature and the development of one's talents, is the surest path to happiness.
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http://www.thelifefiles.com/2009/09/11/huh/