 Quine intended the predicate functor language to lead to a novel algebraization of first-order logic. While bound variables can be eliminated using predicate functors, Quine never defined an algebra in the usual sense—something similar, for instance, to cylindric algebras. Predicate functors, by design, have a very limited applicability, which has the unfortunate side effect that they seem to be of little interest and not much of use outside their intended context.