In recent days with tensions of a global war running at the highest level in decades, an apocryphal story from Art Cashin has been making the rounds across trading desks: one in which the venerable trader explains why when Wall Street was gripped by a selling panic during the Cuban Missile Crisis, the right move was the buy everything: There was the lesson I learned during the Cuban Missile Crisis. At the time I was studying with “Professor Jack” under a Moosehead, in a saloon called “Eberlin’s” down the block from the exchange. The tuition was paid in scotch “old...