Well, now we know: the Scott Brown Era lasted almost exactly three years, from January 2010, when he upset Martha Coakley to win the “Kennedy seat,” and thereby robbed the Democrats of their filibuster-proof Senate majority, imperiled and greatly complicated the prospects for passing Obamacare, and set the stage for the Republican wave the following fall. It ended today, with the surprising word that Brown would not run for the state’s other Senate seat, vacated by John Kerry’s move to be Secretary of State.

And yes, it was an era unto itself. Nobody symbolized better than Scott Brown the dismay and anxiety that beset Democrats and liberals a year or so into Barack Obama’s presidency and has only recently started to lift, following his reelection. It is hard, even now, to overstate the shock of the victory by this back-bench state senator, a former nude Cosmo center-fold who had dared to mock the whole notion of a “Kennedy seat” in his debate against Coakley, who so brazenly flaunted an anti-intellectual, regular-guy shtick in a state that had prided itself on the caliber of its political elites.

The Tea Party in Massachusetts! Never mind that Brown’s late surge was driven more by a flood of Wall Street dollars than by tea-partier pluck; never mind that Candidate Coakley embodied the worst sort of upper-crust establishment-pol complacency. No, if Scott Brown had won in Massachusetts, then bad things surely lay ahead. And of course they did: a Democratic wipe-out in November 2010, the effects of which will be felt for the next decade to come in Congress and state legislatures, thanks to the wonders of decennial redistricting.

The surest sign of how deeply Brown’s win had cut was the recurrence of Democratic anxiety over Kerry’s aspirations to become secretary of state. Was the White House so foolhardy, went the cry, to create another opening in Massachusetts for the diabolical Scott Brown to seize? From the start, this panic struck me as somewhat overdone. First of all, Brown had just lost his seat, to a candidate who, while extraordinarily well-funded, had not exactly had the smoothest debut on the campaign trail. Yes, a special election would be different—with lower turnout among the Democratic base that came out in droves for the presidential election. What was overlooked by the worrywarts, though, was that the circumstances would also almost surely be different than they had been in the last special election, which arrived just as unease over Obama and the lousy economic recovery was starting to crescendo, and which, crucially, was set up to be such a perfect way to deliver a symbolic and consequential rebuke.

This will not be the case for the special election this June, even if things turn somewhat against Obama in the months ahead and even if the Democratic nominee (so far, Reps. Ed Markey and Stephen Lynch are vying for the spot) turns out to be less than scintillating. Times, quite simply, have changed. Not only did Obama win reelection, but it is the other party that is now on the wrong side of the general public mood on any number of issues, from the fiscal morass to guns. Democrats should never have worried so much about having to defend an open seat in a state where Obama won 61 percent against the state’s former governor. A longtime senator with a yen for being secretary of state should have been able to put himself forward for that without setting liberal alarm bells ringing about the fate of the seat he would leave open.