sentences:  The names that he used for his own categories varied with context and occasion, but ranged from reasonably intuitive terms like "quality", "reaction", and "representation" to maximally abstract terms like "firstness", "secondness", and "thirdness", respectively.Taken in full generality, "nth"-ness can be understood as referring to those properties that all "n"-adic relations have in common.Peirce's distinctive claim is that a type hierarchy of three levels is generative of all that we need in logic.