At Philadelphia in 1787 Mason was one of the five most frequent speakers at the Constitutional Convention. He exerted great influence, but during the last 2 weeks of the convention he decided not to sign the document. Mason's refusal prompts some surprise, especially since his name is so closely linked with constitutionalism. He explained his reasons at length, citing the absence of a declaration of rights as his primary concern. He then discussed the provisions of the Constitution point by point, beginning with the House of Representatives. The House he criticized as not truly representative of the nation, the Senate as too powerful. He also claimed that the power of the federal judiciary would destroy the state judiciaries, render justice unattainable, and enable the rich to oppress and ruin the poor. These fears led Mason to conclude that the new government was destined to either become a monarchy or fall into the hands of a corrupt, oppressive aristocracy. From a biography posted here.
Unquestionably, the most important Founding Father nobody knows.
You're right about that.
I knew someone objected, but I had forgotten it was him! If we hadn't had the bill of rights, things would have definitely been different! Major impact, long forgotten by name.