The substance is a question related with the being, that can par excellence be considered the Metaphysical question. For the philosophy of Aristotle to ask on what it is the Being is the same that to ask what it is the substance; the substance for the master of the 2 secondary school, is everything what it exists, therefore everything what it exists is substance or the sensation of the substance. According to old conception of metaphysics had a multiplicity substances, which were commanded hierarchically. Spinoza going as that in the one against hand of the multiple substance conception assevera that a substance only exists, namely, God. God, who is the substance, the first bedding of all the things, not needing to send exactly to no being beyond itself, therefore is cause of itself exactly, therefore, such reality cannot be conceived as not existing. It writes Spinoza in the third definition: ‘ ‘ For substance I understand what it exists exactly in itself and by itself it is conceived, that is, that whose concept does not demand the concept of another thing of which it must be formado.’ ‘ The clear substance idea is of a being that does not lack of nobody to subsistir, it is the perfect being that subsiste for itself. Of this substance definition, she is necessary to affirm its real existence, because if we denied the existence to it, in a similar way we would destroy the definition, therefore, for its definition it is for its existence as real. for if having this intuition of the clear and distinct definition for idea, that can be considered infallible, we know that the substance exists necessarily in the reality.