The 19th Century New England author Thoreau provides an approach to conscience and unjust laws approximating that given by St. Thomas Aquinas in _Summa Theologiae_. But the portrait of conscience given by Thoreau in the 1848 oration “Civil Disobedience” is incomplete. Thoreau’s approach is solved by accepting insights given in Part I and Part I–II of _Summa Theologiae_. Allowing St. Thomas’ insights requires reform of Thoreau’s civil disobedience and conscientious objection. But Thoreau’s arguments are given new life.