Before starting the study on the four causes and the slight knowledge of principle in Aristotle, she is necessary to have an idea of what it is and what consists its metaphysics. Made this, I will treat to display the subject considered and central of our study that is the briefing of the four causes with the principle notion. Aristotle, according to Giovanni Reale, divides sciences in three parts, the theoretical ones, practical and the productive poiticas or, being the most important of them theoretical ones, that they are constituted by the mathematics, the physics and metaphysics. This last one being most important of all, ' ' therefore he is of it and in function of it that all other sciences acquire significado' just; '. (1) First philosophy was the name that Aristotle gave to its science, later called of metaphysics for posterior thinkers it. The term first philosophy was used for Aristotle in opposition to the philosophy second, that is, to the physics.
E since it is in opposition to the physics could not have another name Metaphysical seno. Metaphysics is the study of what it is beyond the physics, of everything what the physics cannot explain. Therefore, it studies the supply-sensible universe, the being and the truth of the being. Supply-sensible in what he says respect to the holy ghost, the same God, since for Aristotle, being is substance and God is the first substance that cause all the others. Reale says that ' ' research on God is not alone a moment of the Metaphysical research, but it is the essential moment and fundador' ' (2) e, if did not exist a supply-sensible substance also would not exist metaphysics and the physics would be the first philosophy. Metaphysics is a free science, therefore it finds in same itself its end, that is, its purpose and, its objective and its object are not in material things as in other sciences, but in same itself.