The substance is infinite. If the substance definition is the being that exists for itself, is impossible that at the same time he is ' ' not ser' '. For Spinoza idea of one to be finite corresponds to the idea of not being, and if it is to be is not limited, and if it is limited it cannot be perfect, therefore, it is impossible that the substance is finite, therefore for definition is infinite. It writes Spinoza in Proposal 8: ' ' An only substance of same attribute (for prop does not exist seno. 5), and to its nature belong existing (for prop. 7).
To its nature, therefore, existing, or as finite will belong or as infinite. However, it could not be as finite, therefore (for def.2), in this in case that it would have to be limited by another one same nature, which also would have necessarily to exist (prop. 7). They would exist, then, two substances of same attribute, what it is nonsense (for prop. 5).
Soon, it exists as infinita.' ' The substance is only one second substance is only possible if to distinguish from the first one. But so that this occurs she is necessary that the first one possesss a perfection that it does not possess second; it is necessary that this second substance involves to be and either finite, what is impossible, therefore does not finish to demonstrate to be any infinite substance. This substance, according to Spinoza, is God, necessary, infinite and only, simple, invariant and independent the Being par excellence. It writes Spinoza in proposal 5: to ' ' If two existed or more distinct substances, them would have to be distinguished enter itself for the difference of the atribtos or the difference of the afeces (for proposal 4). If they distinguished themselves only for the difference of the attributes, are of if admitting, then, that seno does not exist an only substance of same attribute.