Riddle - Mar 29

I’m as a dare—If just you’ll come along, and give my noble providence a shot, seeing what boundless bounty might be got, you’ll sing me a river, cry me a song. So if you trust that I can do no wrong, and yield yourself to untying this knot, finding this vacant vessel full of thought, you’ll sing me a river, cry me a song. Another hint may here do well to tell: I am music not written for the ear, a painting—that I am—though not in view. Being seen, being heard, casting my spell, I fascinate; this is my blissful sphere. So know you now, which fancy sings to you?