…the only kind of relation which could be veritably described to a person who had no experience of it is a relation of reason. A relation of reason is not purely dyadic: it is a relation through a sign: that is why it is dicible. Consequently the relation involved in duality is not dicible, but surd; and duality must contain as an ingredient of it a surd disquiparance.
http://www.commens.org/dictionary/entry/quote-basis-pragmaticism-3