With future perfect (F2) you jump to a point in the future, turn round and say some action is finished then. Actually a complicated thing and cumbersome and in most cases you can express the same idea much simpler without using F2. This tense existed in Latin and it was imitated by writers.
In current English usage, muse can refer in general to a person who inspires an artist, writer, or musician.
Definition of muse. 1  1 capitalized : any of the nine sister goddesses in Greek mythology presiding over song and poetry and the arts and sciences Clio is the Greek Muse of history. 2  2 : a source of inspiration; especially : a guiding genius The writer's beloved wife was his muse. 3  3 : poet.