In my opinion, the great figure of a council, means — the grand machine, i.e.
1 take up the Author's words, where he speaks of the great figure of a council.  In my opinion, the great figure of a council, means — the grand machine, i.e.  the collective body of the council, that gives movement to the many figures of a state, and by whose operations the govern ment of a realm is duly maintained, according to the chartered covenant between the king and the people.