Name That Prez

Who wrote the following about which American president?

“Careless and incontinent of speech, he was continually making mistakes; carried away by his first impression, which was always chivalrously lofty, he would suddenly remember his position and turn back half way. He was an even greater failure in these diplomatic countermarches than in metaphysics and nomenclature; and, having got his legs tangled in the traces once, he would do it two or three times more in trying to get clear. He was blamed for this; people are so superficial and inattentive that they look more to words than to actions, and attach more weight to separate mistakes than to the combination of the whole character.”