He created Pennsylvania ... and the constitutional amendment! From wikipedia:
More from Quaker.org:Over twenty drafts, Penn labored to create his “Framework of Government.” He borrowed liberally from John Locke who later had a similar influence on Thomas Jefferson, but added his own revolutionary idea—the use of amendments—to enable a written framework that could evolve with the changing times.
Penn's "First Frame of Government" was the first constitution to provide for peaceful change through amendments. A proposed amendment required the consent of the governor and 85 percent of the elected representatives. Benevolent though Penn was, people in Pennsylvania were disgruntled about his executive power as proprietor and governor. People pressed to make the limitations more specific and to provide stronger assurances about the prerogatives of the legislature. The constitution was amended several times. The version adopted on October 28, 1701 endured for three-quarters of a century and then became the basis for Pennsylvania's state constitution, adopted in 1776.
