Matter is related to
verbal processes; it is the circumstantial equivalent of the Verbiage, ‘that
which is described, referred to, narrated, etc’. The interrogative is what
about?. Matter is expressed by
[prepositional phrases introduced by] prepositions such as about, concerning, with reference to and sometimes simply of … It is frequent with both ‘verbal’
clauses and ‘mental’ ones (especially of the ‘cognitive’ subtype).