Modern people tend to see knowledge as something humanity achieves collectively and then keeps forever. Once a scientific advance or moral truth is discovered, we assume it becomes part of the species’ permanent inheritance. That is false. Tradition is not a museum display. It is not a costume we wear on patriotic holidays. It is a discipline. Truth may be eternal, but our knowledge of it is not. Knowledge can be lost when a civilization stops practicing it. As America celebrates its 250th anniv