We may say that in language (11) we have various parts of speech. For the functions of “slab” and “cube” are more alike than the functions of “slab” and “d”. But how || the way we classify the words together as various parts of speech will depend on the purpose of the classification, and on our inclination.
     Think of the different points of view from || according to which one might classify tools as different kinds of tools. Or chess pieces as different kinds of pieces.