Second Intentional Logic
The scholastic doctors used to talk of first intentions and second intentions. First intentions were conceptions obtained by generalizing ordinary experiences. Second intentions were conception[s] obtained by generalizing conceptions themselves considered as objects of logical comparison. Now an abstract notion, that is, the name of a quality, is the first fruit of second-intentional thought. I have therefore called that branch of formal logic which takes account of this operation, and expresses it, Second Intentional Logic.