Why H. P. Grice titled Part II to his "Way of Words" as "Semantics and Metaphysics"

“If it is necessary to invoke the notion of a ‘category,’ am I to suppose this ‘category’ to be a linguistic category (a category of expression) or a metaphysical category (a category of things), a question which is plainly close to the previously-mentioned burning issue of whether the theory behind ‘ordinary’ discourse is to be thought of as a highly general, language-indifferent, semantic theory, or a metaphysical theory about the ultimate nature of things, if indeed these possibilities are distinct.”