His testimony today suggests two possibilities: that he really is senile, or that he is pretending to be so in order to avoid having to explain his conduct as Special Prosecutor. If the latter is true, it had to do with his reluctance to discuss his decision to hire a host of hyper-partisan Democrats, such as Andrew Weissman, to do the footwork on the case and with his failure to investigate the origins of the Fusion GPS report and to consider the possibility that the Russians made clever use of the Clinton campaign.

Donald Trump is an impulsive man. He knew that he was innocent of the charge being weighed by the Special Prosecutor, and he rightly discerned from the outset that Mueller’s appointment was a ploy aimed at his ouster. That this would enrage a man of his temperament is no surprise. But let’s face it. If you were on the receiving end of such treatment, you would be more than annoyed. That Trump would thrash about seeking the means for getting off the hook also makes sense, as does his rancor against Jeff Sessions, who allowed himself to be bulldozed by the staff of the Department of Justice. But, in the end, Trump did nothing to interfere with the investigation.