If you live long enough, life presents you with delicious ironies, like Jeb Bush becoming the “last reasonable Republican in America.”

He has captured the imagination of a media eager to validate the truism that there are equal measures of reasonableness and madness on both sides.

Yes, the same Jeb Bush who perfected the kind of massive voter purges that his lesser understudy, current Florida Gov. Rick Scott, is blundering through. Jeb’s version even featured the same flawed name matching — against lists of felons — versus Scott’s clumsy mash-up between Hispanic and other “foreign-sounding” surnames and the crack efficiency of the DMV. Of course, Jeb never managed to get sued by the feds for violating the Voting Rights Act.

The same Jeb(!) who developed a reputation as something of a Capitol bully — canceling affirmative action in Florida by fiat, then demanding that state police kick protesting lawmakers’ “asses” out of his office — is now a paragon of reasonableness, advocating political compromise.

The Bush who never met a corporate tax cut he didn’t like, and who even advocated giving taxpayer money to families to send their children to religious schools — that guy — is now too liberal for the GOP for hinting that a 10-to-1 ratio of spending cuts to revenue (tax) increases isn’t the essence of Marxism.

And that makes him, by default, the sanest guy in the Republican rubber room.

Jeb became an apostate according to the new bosses of uber conservatism, and a fakey, liberalish RINO (Republican in Name Only) for criticizing the hyper-partisanship that has caused a plurality of voters to believe, according to the latest Public Policy Poll, that Republicans are deliberately harming the economy just to beat President Obama.

Jeb mentioned that in the past, even in the halcyon Reagan era, the parties occasionally cooperated on fundamental economic policy, for the good of the country.

He admitted to not pledging his eternal fealty to Grover Norquist by not signing his artfully feudal “pledge” when he was active in politics.

Even before that, Bush the Younger was guilty of serial crimes against the far right: opposing the draconian, Hispanic voter-repelling, “papers” law in Arizona; appearing with The One True Enemy’s education secretary, Arne Duncan; and voicing support for some aspects of Obamaian education reform.

And daring to say what every reasonable observer knows full well to be true: that no Republican president in recent history (or less than recent — Eisenhower championed the interstate highway system and William Howard Taft proposed a corporate income tax and presided over the passage of the 16th Amendment, for God’s sake) not George W. Bush, not George and Jeb’s father, George H.W. Bush, and not even the sainted Ronald Reagan, would pass the conservatism test of the newfangled Republican Party.

All three Republican presidents grew government, both by spending prodigiously and by hiring tens of thousands of government workers to help reverse recessions under their watch. Each pursued, in partnership with Congressional Republicans and Democrats, precisely the kinds of stimulus that Obama did — when the economy faltered during their terms.

Two of those presidents either expressed support for (George II) or enacted (Reagan) comprehensive immigration reform, which in Reagan’s case, meant actual amnesty for illegal immigrants in the country.

All three presided over massive federal budget deficits, and their apparatchiks, including one Richard “Dick” Cheney, stated aloud during that bygone era that “deficits don’t matter.”

Or at least they didn’t, until Barack Obama showed up.

Jeb is now backpedaling a bit from his intra-party critique. But there can be little doubt that had he seized the moment to run for president this year, he would have had two choices. He could do what Mitt Romney has done: subordinate himself to the birther-coddling, talk radio-driven extremists now in control of the once Grand Old Party; erase any semblance of old-fashioned Republicanism in him and promise to be the guy in the White House who merely grips the pen that signs whatever Norquist puts in front of him. Or he could be Jon Huntsman.

No wonder Jeb didn’t run.