  One standard objection to type-(2) theories is that the abstractness of boundaries seems to run afoul of the abstractness of set-theoretic constructions. One can see and paint the surface of a table, and one can even see and paint an infinite series of ever thinner layers of table-parts. But one cannot paint the set of these parts (unless of course this is simply another way of saying that the parts are painted). Indeed, Theodore de Laguna, one of the very first sponsors of Whitehead's method, remarked that the identification of points and other boundaries with classes of solids is open to serious misinterpretation: “Although we perceive solids, we perceive no abstractive sets of solids […] In accepting the abstractive set, we are as veritably going beyond experience as in accepting the solid of zero-length” (de Laguna 1922: 460).