The Caligulan malice with which Donald Trump administered Paul Ryan’s degradation is an object lesson in the price of abject capitulation to power. This episode should be studied as a clinical case of a particular Washington myopia — the ability of career politicians to convince themselves that they and their agendas are of supreme importance.

The pornographic politics of Trump’s presidential campaign, which was preceded by decades of ignorant bile (about Barack Obama’s birth certificate and much else), have not exhausted Trump’s eagerness to plumb new depths of destructiveness. Herewith the remarkably brief timeline of the breaking of Ryan to Trump’s saddle.

On May 3, Trump won the Indiana primary, ending competition for the Republican nomination. On May 5, Ryan said he still was not prepared to endorse Trump. That day Trump responded that he was not ready to endorse Ryan’s agenda. This was not news, considering that Trump has campaigned against every significant element of this agenda — entitlement reform, the rule of law, revival of Congress as a counter to the executive overreach that Obama has practiced and that Trump promises to enlarge upon.

On May 12, a Trump meeting with Ryan resulted in a cringeworthy joint statement that had to be read to be properly disbelieved. The two spoke about the “great conversation” they had about “our shared principles.” They celebrated their “many important areas of common ground” while offhandedly mentioning “our few differences.” Those who know, or thought they knew, Ryan doubted that he could name a single shared principle, and he did not do so.

In spite of, and in conspicuous dissonance with, the May 12 happy talk, Ryan continued to withhold his endorsement. Perhaps he hoped that Trump, at age 69, was going to mend his manners.

1 of 23 Full Screen Autoplay Close Skip Ad × 23 well-known people who support Donald Trump View Photos See who supports Donald Trump. Caption See who supports Donald Trump. Paul D. Ryan The House speaker endorsed Trump’s bid for president on June 2. Joshua Roberts/Reuters Buy Photo Wait 1 second to continue.

Instead, Trump dragged a personal problem, his coming trial on fraud charges associated with Trump University, into the presidential campaign. Having first done so in February, on May 27 he again attacked the “Mexican” judge (born in Indiana, 1,332 miles from Mexico) who will preside at the trial, asserting that the Hoosier Mexican was unfit to preside because his ethnic heritage would incline him against Trump, the wall-building scourge of Mexican rapists. On May 30, Trump again attacked the judge, again embracing the identity politics that actually characterizes contemporary progressivism: An individual has, always and only, the interests and motivations of his race, ethnicity, gender or sexual orientation.

By June 2, Ryan had heard enough. He endorsed Trump. He did so because President Trump would sign Ryan’s House “agenda.” Well.

Since May 5, the Hamlet of southeastern Wisconsin had indeed learned something. He had learned Trump’s contemptuous response to his scruples. Trump’s response was an insouciant intensification of his anti-institutional politics — the judicial system, too, is “rigged.” Ryan limply described Trump’s attack on the judge as thinking “out of left field” that he could not “relate to.”

All supposedly will be redeemed by the House agenda. So, assume, fancifully, that in 2017 this agenda emerges intact from a House not yet proved able to pass 12 appropriations bills. Assume, too, that Republicans still control the Senate and can persuade enough Democrats to push the House agenda over the 60-vote threshold. Now, for some really strenuous assuming: Assume that whatever semblance of the House agenda that reaches President Trump’s desk is more important than keeping this impetuous, vicious, ignorant and anti-constitutional man from being at that desk.

Some say in extenuation of Ryan’s behavior that if he could not embrace Trump, he could not continue as speaker. But is Ryan, who was reluctant to become speaker, now more indispensable to the nation’s civic health than Trump is menacing to that health? Ryan could have enhanced that health by valuing it above his office.

In March, Trump said of Ryan: “I’m sure I’m going to get along great with him. And if I don’t, he’s going to have to pay a big price.” Ryan has now paid a staggering price by getting along with Trump. And what did Ryan purchase with the coin of his reputation? Perhaps his agenda.

In Robert Bolt’s play “A Man for All Seasons,” Thomas More is betrayed by Richard Rich, who commits perjury to please the king, in exchange for being named attorney general for Wales. Says More: “Why Richard, it profits a man nothing to give his soul for the whole world. . . . But for Wales?” Or for the House agenda?

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