Spinoza's first proposition is that "substance is by nature prior to its affections" (Cahn p.417). This proposition relies on his definition of a substance which is self created. The affections of the substance, according to his definition, are things that are created by something else. Since the substance is self-created, the substance must have created the affections from itself. Therefore, the substance is prior to its affections since the substance has to be in existence to create its affections.

Proposition 2, "two substances having different attributes have nothing in common" (Cahn p.417), also relies on the definition that a substance is self-created. If one attribute of a substance is created from that substance,

Proposition 2, "two substances having different attributes have nothing in common" (Cahn p.417), also relies on the definition that a substance is self-created. If one attribute of a substance is created from that substance, it belongs only to that substance. Therefore, two different substances having the same attribute are not different, but the same substance. If two substances are truly different, they have none of the same attributes. If all the attributes of the two substances are completely different, they have nothing in common. One thing, which is completely different from the other, cannot have caused the other. This is true because something created must have some knowledge of its creator, as stated in Spinoza's axiom 4. Since the two different things have nothing in common, which includes no knowledge of the other, one cannot have created the other. Spinoza states this in proposition 3. "When things have nothing in common, one cannot be the cause of the other" (Cahn p. 417). He also reaffirms this in proposition 4 by stating that things are different by the fact of differences in their attributes or affections. This fact is seen easily by looking at the proofs beforehand of propositions 1,2, and 3.

Now Spinoza proves that God exists in proposition 11: "God, or substance consisting of infinite attributes, each of which expresses eternal and infinite essence, necessarily exists" (Cahn p.419). He easily proves this using axiom 7: "if a thing can be conceived as not existing, its essence does not involve existence" (Cahn p.416). He says it is absurd to conceive God as nonexistent since existence belongs to the nature of God, or substance (proposition 7). He also says that there is no substance that can prove that God does not exist since two different substances have nothing in common (proposition 2). Therefore, God exists.

This paper will outline Spinoza's argument in Part 1 of his Ethics of substance. He argues that there is only one substance, which is the same as God, that includes everything in the universe. It will walk through each proposition and explain his proof of it, which relies of his stated definitions. This paper will also explain the difference between Spinoza's belief of substance and that of Leibniz from his Discourse on Metaphysics. It will then argue that Leibniz's account of the number of substances superior.

Spinoza now proves proposition 14; that no other substance other than God exists. Since God is an absolutely infinite being, any other existing substance would have to exhibit an attribute of God. This is impossible because no two substances can exist with the same attribute (proposition 5). Existence is an attribute of God; therefore no other substance can exist.

Leibniz's account of the number of substances is superior. The many monads, each with its own attributes, allows for the many different things in the universe to exist. Since everything does not have all the same monads, they can be different. A dog and a rock are obviously not the same. They are not the same because they are composed of monads with different attributes. If they did consist of the same monads, they would be the same, and they obviously are not. According to Spinoza, God is the only substance. Everything we know is part of God. God includes all attributes. If I am part of God, I contain all attributes. However, I do not contain all attributes. There are many that I do not include such and infinity. I am obviously not infinite. Leibniz's account of the number of substances allows me to exist, not containing every attribute.

Since Spinoza has proved that there is a unique, infinite substance that exists, he now goes on to prove that the substance is God, only one of which exists. He must first include some propositions, which will be used later to help prove this point. He begins by proving that the more real some

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