That’s an idea, but not the only one, that emerges from two small exhibitions that Yale University is mounting to mark the centennial of the War to End All Wars. “Yale Medicine Goes to War, 1917” and “Refugees, Immigration, and Library Books for Soldiers: A Selection of World War I Posters” are on view in the corridor and in the rotunda of the John Hay Whitney Medical Library over on Cedar Street at the medical campus.