quiddity, when taken without qualification, with neither existence nor nonexistence stipulated, being the cause of its own existence. Quiddity as such is neither existent nor nonexistent.

I say: The argument rests on the assumption that the unrestricted, shared universal exists in external reality. This is precisely where their minds went astray: they believed that particular existing things share something in external reality, while each is distinguished from the others by something else. This is the very error.

I say: A particular individual has no individuation distinct from that very individual, whether positive or privative. It does not share any externally existing reality with another such that its individuation and distinction from that other would require an additional positive or negative attribute.

Their general rule is false, namely: “Things sharing a definition of their species differ only through other causes. If an instance lacks the capacity to receive the effects of causes—namely, matter—it cannot be individuated unless its species is by its very nature such as to exist as a single individual. But if the nature of its species allows it to be predicated of many individuals, each is individuated by a cause. Thus, two instances of blackness or two instances of whiteness cannot exist in reality unless they differ in their underlying subjects or in something serving the same role.”

For things sharing one and the same definition of their species do not exist in external reality as unrestricted or general entities at all; they exist as such only in the mind. The efficient cause of any one of them brings about the individual itself and its attributes; it brings about that particular individual. There are not two things here, one corresponding to its species and the other to its individuation; nor are there two existences, one corresponding to its species