George Washington had a warning for the Senate as it considers impeachment

Donald Trump claims to be “the greatest president in the history of our country,” better than Lincoln or Washington, and Republicans seem to agree. And yet, one of the most important foundational texts in U.S. history, written by one of those “lesser presidents,” warned about figures like Trump and the danger they pose to the United States.

George Washington’s Farewell Address is largely forgotten today, as its most emphatic caution — to avoid foreign entanglements — seemed increasingly outmoded as the United States became a global power. But Americans once...