Out of the corner of his eye, Paul Ryan must frequently see the Robert A. Taft Memorial and Carillon at the base of Capitol Hill. The bell tower memorializes a senator who so embodied his party that he was called “Mr. Republican.” He was the son of a president, wanted desperately to be one himself, and yet on Oct. 5, 1946, risked everything on a matter of principle. He denounced as un-American the trial and the impending execution of 11 high-ranking Nazis. It was a futile act. Within two weeks, 10 were hanged and one committed suicide.

Republicans, appalled, ran for cover. Democrats unleashed a fusillade of cheap shots. The wounded and dead of World War II were cited. The millions of veterans were embraced. The full horror of Nazi crimes so recently placed into evidence at Nuremberg was exhumed, and Taft, an uncommon man of uncommon courage, was vilified. He had his principles, though, and he stuck to them. The Constitution commanded no ex post facto laws. The Nazis were convicted of waging an aggressive war — a crime without legal precedent. Taft was adamant that they had broken no existing law.

In his Pulitzer Prize-winning book “Profiles in Courage,” John F. Kennedy included Taft among those senators he chose to honor. As was his wont, Kennedy did not say whether he agreed with Taft — the book was published in 1956, when Kennedy was hoping to become the next vice presidential nominee (Eleanor Roosevelt wished Kennedy had “less profile and more courage”) — but he did say how much he respected Taft’s stand on principle. It is enough for me, too.

Ryan wrote that he would vote for Donald Trump so as to secure the Republican Party agenda. Taft put the matter the other way around: First come principles, then comes the agenda. Trump is without principles. Ryan has fewer than he once had.

When Taft gave his speech, the midterm elections were only a month away. The GOP had a chance to take the House and control Congress after having been in effective exile since the election of Franklin D. Roosevelt 14 years before. So much was at stake, so much needed to be reversed, including, of course, the New Deal itself. As much as Ryan and others want to terminate Obamacare and other programs, the stakes for the GOP in 1946 were even greater.

Paul Ryan endorsed presumptive Republican presidential nominee Donald Trump on June 2, but the two haven't always seen eye-to-eye. (Peter Stevenson/The Washington Post)

But to Taft, pesky matters of constitutional principle had a way of vexing him. The Constitution mattered. It mattered more than retaking Congress or repealing the New Deal. The Nazis must not be hanged even though the massacre of 84 American POWs at Malmedy was fresh in American minds and the newsreels of the liberation of Auschwitz and the other camps were still being shown. The Nuremberg trials themselves further inflamed the United States. The 11 Nazis in the dock were not mere criminals. They were the devil in their once-sharp (Hugo Boss) uniforms.

As Ryan showed that his itsy-bitsy legislative ideas took precedence over mere matters of principle, Trump went on an insult binge. He berated and threatened a federal judge of Mexican heritage, continued offending Hispanics, called out to a black person at a rally, “Look at my African American.” Earlier, he had persisted in inventively seeking unity by dividing — white and black, Hispanic and everyone else, Muslim and the whole world, pretty women and ugly women, the disabled and everyone else, and cowardly prisoners of war and those service members who bravely never faced combat.

What I know about Ryan is that he could not be proud of endorsing Trump. He shouldn’t be. Trump will not respect him for his acquiescence (he’ll call him a loser), and neither will anyone else. Ryan puts his legislative agenda above his own principles and the good name of the country so someday he could say, yes, Trump got us into a ruinous trade war but I trimmed a bit off the Affordable Care Act.

Kennedy himself wrote that he did not often agree with Taft yet he found the old man agreeable and always forthright. JFK may still have been bothered by Taft’s refusal to condemn the demagogic Sen. Joseph McCarthy and maybe he was drawing a very personal contrast. Whatever the case, Taft’s political courage certainly contrasts with what we now see on Capitol Hill.

Every hour, the Taft carillon’s bell sounds — “a summons to integrity and courage,” former president Herbert Hoover said at its dedication.

For whom does that bell toll? Not for Paul Ryan.

Read more from Richard Cohen’s archive.