The Constitution itself was understood by its framers as a machine, a precisely constructed instrument whose measures — its separation of powers, its checks and balances — were mechanical devices, as intricate as the gears of a clock, designed to thwart tyrants, mobs and demagogues, and to prevent the forming of factions. Once those factions began to appear, it became clear that other machines would be needed to establish stable parties. “The engine is the press,” Thomas Jefferson, an inveterate inventor, wrote in 1799.