The question of what constitutions should do is deeply connected to what constitutions are. In the American founding conception, a constitution was a fundamental law, hierarchically superior to the decisions of the legislature, and intended to act as a restraint on legislative action. Despite the massive gulf between the ancient Greeks and the Americans, classical Athens offers an important lesson about how the failure to recognize fundamental laws can lead to catastrophic consequences. The evidence suggests that the Athenians understood the (...) need for conceptual, procedural, and institutional distinctions between the fundamental laws and the more specific decrees of the governing institutions. The Athenian and American experiences also suggest that certain philosophical positions conditioned their understanding of their fundamental laws, and guided the practices that followed from that understanding. (shrink)