fill in the blanks

first verse of " sailing to byzantium" by william butler yeats :

that is ___________. the young in one another's arms, birds in the trees.
-those dying generations- at their song,
the salmon falls, the mackrel crowded seas,fish , flesh or fowl, commend all summer long.whatever is begotten, born and dies.\caught in the sensual music all neglect
monuments of unaging intellect