The question of the purpose of one's own life and is there a purpose at all the man is asking since ancient times. We can say that the question of purpose is one of the existentially most important issues that man faces. At that trail, the author of this paper, the question of the purpose and purpose of all that is, found in the teaching of Thomas Aquinas, one of the great philosophical thinkers. However, in order to exhibit the Aquinar's concept of purposes, it was necessary to present several preliminary notes about teleology and its beginnings. Moreover, it was necessary to expose Aristotel's doctrine of four causes. Namely, Aristotle's teleological doctrine has accepted and deepened Tom Aquinas, at which we find the link between the first cause and Fist cause. Aquinas is the only one, as it is considered, that exposed complete the doctrine of the purpose. In other words, the doctrine of the purposefulness at Aquinas covers the entire reality that involves the nature that surrounds us, but also a man with all his dimensions. The significance of this kind of purpose is great because, on the one hand, it answers questions about human purpose, and therefore responds to a specific human quest for happiness. On the other hand, it explains the meaning, purpose and action of the entire nature that is purposeful. For the Aquinas's key of purpose is in God that is understood as a source of life, but also as a final and fulfilment of all the purposeful aspirations of everything that acts according to some goal, or everything that is and what is being in existence.