God can only with great impropriety be called one or single, I answer that a thing can only be called one or single in respect of existence, not in respect of essence. For we do not conceive things under the category of numbers, unless they have first been reduced to a common genus. For example, he who holds in his hand a penny and a crown piece will not think of the twofold number, unless he can call both the penny and the crown piece by one and the same name, to wit, coins or pieces of money. In the latter case he can say that he holds two coins or pieces of money, inasmuch as he calls the crown as well as the penny, a coin, or piece of money. Hence, it is evident that a thing cannot be called one or single, unless there be afterwards another thing conceived, which (as has been said) agrees with it. Now, since the existence of God is His essence, and of His essence we can form no general idea, it is certain, that he who calls God one or single has no true idea of God, and speaks of Him very improperly.
negation and not anything positive, it is plain that the whole of matter considered indefinitely can have no figure, and that figure can only exist in finite and determinate bodies. For he who says, that he perceives a figure, merely indicates thereby, that he conceives a determinate thing, and how it is determinate. This determination, therefore, does not appertain to the thing according to its being, but, on the contrary, is its non-being. As then figure is nothing else than determination, and determination is negation, figure, as has been said, can be nothing but negation.
The Hague, 2 June, 1674.