this DC refers to the musics and life of Christoph Willibald (von) Gluck (1714-1787), who appears in the picture three times - can you see?
across, i have spaced out 73 elements - one for each year of his life.
his beautiful music was created in most turbulent times - at his death the Revolution was only 2 years away and his favourite pupil had her head chopped off a few years later.