Seventy years ago a U.S.president threatened violence against a blameless American citizen. The principles in this historical drama are President Harry Truman; his daughter, singer Margaret Truman; and famous music critic Paul Hume.

Margaret sang in a Washington, D.C. concert. Hume wrote that she was a poor singer. The president wrote what would these days be called a hate message:

"Some day I hope to meet you. When that happens you'll need a new nose, a lot of beef steak for black eyes, and perhaps a supporter below!"

Later on, one of our great institutions, the free market, suggested Hume was correct. Margaret was a poor singer. Later still, Hume and Truman met and got along cordially.

I leave it to the reader to decide if there's a tiny, but useful, lesson for 2019 America in all this.