I often go to concerts in Redpath Hall at McGill, but usually at night. An afternoon concert allowed me to admire the stained glass windows. This is the top part of one of three long windows. Music has had a place in universities since the Middle Ages when music theory was taught as one of the liberal arts. The men under the musician are composers - the names that can be seen are Pergolesi, Purcell, Palestrina and Monteverdi. I suspect, the white wigged gentleman is none other than Bach.
Should that be true, he was looking down on a concert of music by his son, C.P.E. Bach whose music has echoes of his father's, but in a very different style. A young harpsichordist, Mahan Esfahanis directed the orchestra from the harpsichord and then played incredibly.
Learn about him here.