So common sense should tell senators that, even if Trump is acquitted in a short-circuited trial, that won’t prevent the evidence from revealing whether an acquittal was a just one. If Republican senators cut the trial short, they run the risk of being refuted and shamed on the pages of history by the very evidence they sought to suppress.

But that’s not the only practical reason they shouldn’t cut the trial short. A second reason — perhaps the ultimate reason — is President Trump.

For the extraordinary evidence of the Ukraine scandal isn’t a one-off. Putting his interests above the nation’s is what Trump instinctively does.

Trump’s written tirade to Pelosi confirms the point: It shows that, even as he is being impeached, he still has no idea why — and thus no idea what his presidential duties require. He hasn’t learned his lesson, and never will.