Frege

A couple of decades later, Gottlob Frege with his "Begriffsshrift" and then Bertrand Russell and A.N.

We were at pains to explain that the number sense is sensitive to properties that are unique to number, however—for instance, the description relativity isolated by Gottlob Frege.

This is precisely what we find when we apply Frege's insights.

In his work on the foundations of arithmetic, Frege noted that numbers are unique in that they presuppose a way of describing the stuff they quantify.

Frege observed that other quantities aren't like this.