According to art historian Helen Gardner, the scope and depth of his interests were without precedent in recorded history, and "his mind and personality seem to us superhuman, while the man himself mysterious and remote".
Kunstiajaloolase Helen Gardneri sõnade järgi olid tema huvide ulatus ja sügavus pretsedenditud ning "ta mõistus ja iseloom paistavad meile üliinimlikud, mees ise salapärane ja kauge".