The central constitutional mechanism safeguarding our liberty is the separation of powers. It is Mother’s Rule writ large. Mother has one slice of pie and two hungry sons. How does she cut the pie so that both brothers are satisfied? One slices, and the other chooses. The ambitions of one perfectly counter the ambitions of the other. One cannot abuse his powers precisely because of the powers accorded the other.

Thus with our Constitution. One brother makes law but cannot enforce it; the other enforces law but cannot make it. One brother declares war but cannot wage it; the other wages war but cannot declare it. One brother appropriates money but cannot spend it; the other spends money but cannot appropriate it.