He knows there is someone or something out there that has weird and exceptional abilities.
He is such an exceptional boy.
Even an exceptional salesperson has an imperfect memory.
He was always hearing such words as: "With your remarkable kindness," or, "With your excellent heart," "You are yourself so honorable Count," or, "Were he as clever as you," and so on, till he began sincerely to believe in his own exceptional kindness and extraordinary intelligence, the more so as in the depth of his heart it had always seemed to him that he really was very kind and intelligent.
Some people have exceptional abilities we do not understand—for example, savants.