We still do not know what hold Vladimir Putin has upon President Trump, but the whole world has now witnessed the power of its grip.

Russia helped Donald Trump into the presidency, as Robert Mueller’s indictment vividly details. Putin, in his own voice, has confirmed that he wanted Trump elected. Standing alongside his benefactor, Trump denounced the special counsel investigating the Russian intervention in the U.S. election—and even repudiated his own intelligence appointees.

This is an unprecedented situation, but not an uncontemplated one. At the 1787 convention in Philadelphia, the authors of the Constitution worried a great deal about foreign potentates corrupting the American presidency.