So much for the notion that the second 100 days would be calmer or more reassuring.

As April drew to a close, and with it the artificial marker of the first 100 days of the Trump presidency, it was possible to conjure a relatively comforting scenario: It could have been worse.

After all, President Trump launched his administration with the dangerous duo of Michael Flynn as national security adviser and Stephen K. Bannon ascendant. The 100-day period ended with Flynn fired, Bannon diminished and the new national security adviser, H.R. McMaster, joining forces with Defense Secretary Jim Mattis to provide a protective buffer against presidential impulsiveness.

Meantime, notwithstanding atrocities such as the immigration orders and the House health-care plan, Trump backed away from some of his most jarring and irresponsible campaign-trail promises and rhetoric, from declaring NATO “obsolete” to labeling China a currency manipulator to moving the U.S. Embassy in Israel to Jerusalem.

A 70-year-old man does not change his character or basic approach. Still, the immense responsibility of the presidency molds its inhabitant. Thus, it was possible to detect some glimmers of maturation and even learning. Health care turned out to be more complicated than anyone knew. Heartbreaking photos of dead Syrian children killed by chemical weapons managed to evoke previously unseen empathy.

(Jenny Starrs/The Washington Post)

Not that the first 100 days had been even in the exurbs of normal, with the inaugural invocation of “American carnage”; the flood of ego-boosting untruths, from the inflated crowd size to the purportedly fraudulent popular vote; and the reflexive assault on enemies, including a “so-called judge” and the Obama administration for its supposed wiretapping plot.

Still, in resolutely optimistic moments, you could imagine a White House whose learning curve would continue an upward climb, however gradual and episodic, in which the New York moderates — Jared Kushner, Ivanka Trump, et al. — would elbow aside the America Firsters.

No longer.

True, the institutions of U.S. government and society have proved relatively robust. The courts and the media have risen to the constitutional occasion; Congress not so much, and intramural GOP dysfunction has so far prevented the worst from being legislated.

But Trump himself is turning out to be the full-fledged disaster of our worst fears. He understands nothing and is uninterested in learning anything — not just the dreary substance of things such as tax reform but constitutional values, governing norms and the United States’ unique role in the world.

He sees things only through the distorting prism of an all-consuming ego. There is only one Trump instinct — “fight, fight, fight,” he said at the Coast Guard Academy — and one Trumpian dichotomy: friend or foe. He is impervious to embarrassment, no matter how blatant his falsehood. The stain of his behavior spreads to taint anyone within range.

The past few weeks have presented an alarming parade of proof. Authoritarianism? Trump summarily fired his FBI director over “this Russia thing” — after, according to reports, James B. Comey resisted Trump’s demand that he pledge loyalty and declined Trump’s importunings to drop the Flynn probe.

Trump met unapologetically with yet another dictatorial thug, Turkish President Recep Tayyip Erdogan, and remained shamefully silent as Erdogan’s security goons beat up protesters on U.S. soil. No surprise there, from the candidate who urged his crowds to “knock the crap out of” protesters and as president reportedly pressed Comey to jail reporters for obtaining leaks.

Overweening egotism laced with self-pity? Trump used the occasion of the Coast Guard graduation to lament his treatment — “No politician in history — and I say this with great surety — has been treated worse or more unfairly.”

Similarly, in the Trumpiverse, the Russia inquiry and the newly named special counsel represent “the single greatest witch hunt of a politician in American history.” In fact, Trump has only himself to blame — Comey’s firing made the appointment inevitable, and the episode demonstrates the justice system working to allay public fears of political interference.

Dangerous ignorance and lack of preparedness for his post? Without evident forethought, heedless of consideration of the consequences, classically boastful, Trump blurted out code-word information about the Islamic State to the Russians at his Oval Office yuk-fest — and, according to the New York Times, derided Comey as a “nut job” whose firing relieved “great pressure” on him.

The national security and diplomatic establishment shudders at the thought of this man at loose abroad.

It is impossible to know how this disastrous episode in our history will conclude, or how grave the damage will be. But an adage from conservative economist Herb Stein comes to mind: If something cannot go on forever, it will stop. This situation does not feel sustainable for a full four years.

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