«Both Spinoza and Hume reject the principle of the infinity of God in the sense of the unknowability of God.
In Spinoza this rejection is expressed in the proposition that "the human mind possesses an adequate knowledge of the eternal and infinite essence of God." The argument by which he has arrived at this conclusion is not directly and explicitly stated. It may, however, be unfolded as follows:
Spinoza begins by asking himself: What do scriptural philosophers mean when they speak of God as unknowable? They mean, of course, that He cannot be the subject of a definition. And what do they mean by definition? They mean, of course, the Aristotelian kind of definition, which
consists of a genus and a specific difference and which is conceived of as prior to the definiendum and as its cause. Spinoza refers to this kind of definition as that which must "include the proximate cause" and describes it as applying only to created things. Taken in this sense, Spinoza admits that God is indefinable and hence unknowable. It is in this sense that he says "every substance is absolutely infinite," by which, in the context in which he uses this proposition, he means that God is indefinable and unknowable. But God, according to Spinoza, is immediately known by his third kind of knowledge, the intuitive knowledge, for God being anuncreated thing, which is in itself or is the cause of itself, becomes known to us through himself. It is in this sense that he says that "the human mind possesses an adequate knowledge of the eternal and infinite essence of God." Thereby Spinoza challenges scriptural philosophers: You say that the existence of God can be demonstrated only a posteriori, and hence you say that, while His existence can be known, His essence is unknown. I say that His existence can be known a priori, and so His essence is known no less than His existence.»
Harry Austryn Wolfson,
Religious Philosophy A Group of Essays by Harry Austryn Wolfson,
Harvard University Press / Atheneum, 1965,
pp./σσ. 12, 13.