a. The main point then is that Spinoza proves from these Notions that there is only One Substance, God. It is a simple chain of reasoning, a very formal proof. “Fifth Proposition: There cannot be two or more substances of the same nature or of the same attribute.” This is implied already in the definitions; the proof is therefore a useless and wearisome toil, which only serves to render Spinoza more difficult to understand. “If there were several” (substances of the same attribute) “they must be distinguished from one another either by the diversity of their attributes or by the diversity of their affections” (modes). “If they are distinguished by their attributes, it would be directly conceded that there is only one substance having the same attribute.” For the attributes are simply what the understanding grasps as the essence of the one substance, which is determined in itself, and not through anything else. “But if these substances were distinguished by their affections, since substance is by nature prior to its affections it would follow that if from substance its affections were abstracted and it were regarded in itself, _i.e._ in its truth, it could henceforth not be regarded as distinct from other substances.” “Eighth Proposition: All substance is necessarily infinite. Proof: For otherwise it must be limited by another substance of the same nature, in which case there would be two substances of the same attribute, which is contrary to the fifth proposition.” “Every attribute must be conceived for itself,” as determination reflected on itself. “For attribute is what the mind conceives of substance as constituting its essence, from which it follows that it must be conceived through itself,” _i.e._ substance is what is conceived through itself (see the fourth and third definitions). “Therefore we may not argue from the plurality of attributes to a plurality of substances, for each is conceived by itself, and they have all been, always and at the same time, in substance, without the possibility of the one being produced by the other.” “Substance is indivisible. For if the parts retained the nature of the substance, there would be several substances of the same nature, which is contrary to the fifth proposition. If not, infinite substance would cease to exist, which is absurd.”[195]