Hannah Arendt (October 14, 1906 – December 04, 1975)
What he said was always the same, expressed in the same words. The longer one listened to him, the more obvious it became that his inability to speak was closely connected with an inability to think, namely, to think from the standpoint of somebody else. No communication was possible with him, not because he lied but because he was surrounded by the most reliable of all safeguards against the words and the presence of others, and hence against reality as such.
(Speaking of Adolf Eichmann in 1963, but also applicable to Donald Trump in 2017.)