Dear, this piece of music is called Canon, and there are many versions! Canon is my favorite pure music. In fact, it is singing in rotation, with several bars looping continuously! One of the versions is for violin and harp, which is quite nice! A lot of pop music uses canon as its keynote! It sounds very sad when you are sad, and very warm when you feel warm. It is a magical song, right? I have several songs related to it!