Berkeley and nominalists of his stripe deny that we have any idea at all of a triangle in general, which is neither equilateral, isosceles, nor scalene. But he cannot deny that there are propositions about triangles in general, which propositions are either true or false; and as long as that is the case, whether we have an idea of a triangle in some psychological sense or not, I do not, as a logician, care. We have an intellectus, a meaning, of which the triangle in general is an element. (CP 5.181)
(Putting this here mostly so I can easily find the reference again.)
