Random HouseJohn McCain would be the first to tell you that it does no good to whitewash our heroes. In fact, as he has stressed throughout his six published books and untold thousands of media interviews, it’s the imperfections and missteps of our best protagonists, coupled with the arduous and even hopeless natures of their quests, that make them worth studying in the first place.

So as the senior Arizona senator grapples with brain cancer in the wake of blod-clot surgery, and the tripartisan tidal wave of sympathetic affection from Republicans, Democrats, and journalists overwhelms the strangled objections of sour contrarians, allow this critical ideological biographer of the man to suggest that it’s precisely John McCain’s mixture of high-minded virtue and low self-interest, of policy righteousness and interventionist overreach, that makes his a particularly educational example in the era of Donald Trump.

Underlying these past hours’ outpouring of tributes is the sense that McCain is a pre-Trump throwback to honor and decency, that his irascible independence is precisely what our system of checks and balances cries out for as the 45th president crashes through norm after norm. There is some important truth to that—for instance McCain’s global barnstorming tour to reassure America’s nervous allies that United States foreign policy involves more than just the whims of its unpredictable commander and chief. Few people with half his 80 years would have the stamina for such travel, and even fewer would be driven by such patriotic fire to do what he considers the right thing.