This was Germany in the years after World War I, when those who thought Germany had been stabbed in the back hailed the assassination of the industrialist and moderate (Jewish) politician Walter Rathenau in 1922 -- including a failed painter from Vienna named Adolf Hitler.
This was Japan in the 1930s, when advocates of military aggression systematically assassinated moderates who wanted their country to live in peace with its neighbors and not seek conquests abroad.
Or, to take an example from last week, Pakistan, where the governor of Punjab was assassinated. His offense: opposing blasphemy laws that carried a death penalty. Those who supported his assassination celebrated publicly and urged more such killings.
Systematic political assassination can be effective, with horrifying results, as the examples from Germany and Japan show.
And the example from Pakistan shows that President Obama, his administration and members of Congress have a very difficult problem on their hands, more difficult since the sudden death last month of our hugely able diplomat Richard Holbrooke.
Suggestions that the shooting in Arizona are of the same ilk as these examples is something of a blood libel against the politicians of all stripes in our country and of the American people. No American politician, no significant segment of any political movement, no statistically identifiable share of the American people wishes the violent death of its political opponents.
Vivid political rhetoric is always in season, and has been for all the years of our republic. And military metaphors are part of the language of our politics -- metaphors that no serious person takes literally. We should not let it be otherwise, even as we wish for the full recovery of Gabby Giffords and the others stricken and mourn those lost.