Interesting chap! Thomas Jefferson said Mason was the wisest man of our generation.
Mason was certainly no wallflower at the Convention and had a major influence. As for the number of times he spoke, he was a close number four behind Madison, Morris, Wilson.
Despite owning 200+ plus slaves, he was against the institution. I think he would have voted later on for extensive measures against the Slave States’ interests if the Northern States had called their bluff.