As for his argument establishing the existence of what is not perceptible to the senses, he has appealed to universals.

He may be told: You say that a single name applies to these perceptible things on the basis of a single meaning—for example, the name “human being,” which applies to Zayd and Amr on the basis of one existing meaning.

He may then be asked: Do you not mean that this single meaning shared by Zayd and Amr is one meaning existing in a knowing subject, such as a human being, just as the expression “human being” exists in the speaker, and the written name “Zayd” exists on the tablet bearing that writing? Or do you mean that this single meaning exists externally, in Zayd and Amr or in something else?

The first is correct, but provides no evidence for your argument.

As for the second, your claim about the meaning is like the claim of someone who carries your reasoning through and holds that the expression “human being,” which applies to Zayd and Amr, exists externally in Zayd and Amr, and that the writing corresponding to the expression exists outside the tablet, in Zayd and Amr. For every rational person knows that writing corresponds to the spoken expression, that the expression corresponds to the meaning, and that the universal applicability of a single meaning is like that of the single expression corresponding to it.

Thus, when someone says “human being,” the expression exists on his tongue and the meaning exists in his mind. The expression applies to Zayd and Amr just as the meaning does. This is the meaning you called intelligible and regarded as purely intelligible,