His fame hasn’t endured like Washington’s, Jefferson’s, or Hancock’s. But Benjamin Rush—only 30 when he signed the Declaration of Independence—was almost equally extraordinary. He was the most famous physician of his time, pioneering national healthcare and revolutionizing the treatment of mental illness. He was also a progressive thorn in the side of the American political establishment, opposing slavery, capital punishment, and prejudice.

In a discussion of his new biography Rush: Revolution, Madness, and Benjamin Rush, the Visionary Doctor Who Became a Founding Father, award-winning journalist and historian Stephen Fried examines perhaps the most significant Founding Father you’ve never heard of.

Fried is an adjunct professor at Columbia University and the University of Pennsylvania.