This is from Nietzsche’s The Gay Science. I relate very much to this feeling of striving after a vision one can never reach.

“[A poet’s] work never expresses altogether what they would really like to express, what they would like to have seen: they appear to have had the foretaste of a vision and never the vision itself:- but an extraordinary longing for this vision has remained in their souls; and from this they derive their equally extraordinary eloquence of longing and craving.”