What, in your opinion, is the most brilliant piece of music ever written? Defend your choice.

I’m not looking for your favorite. Just the most brilliant in your opinion. My entry is the first movement of Beethoven’s Symphony #5. You all know it; it opens with the G-G-G-Eb motif. What Beethoven did was take that simple four note motif and build an entire symphonic movement around it. It travels far afield from the original four notes, but you hear the rhythm of three 1/8 G notes and the Eb half note over and over in different harmonic tones.