One day I paid him a visit [an orangutan at the Paris Zoological Gardens], accompanied by an illustrious old gentleman, who was a clever, shrewd observer. His somewhat peculiar costume, bent body, and slow, feeble walk at once attracted the attention of the young animal, who, while doing most complacently all that was required of him, kept his eyes fixed on the object of his curiosity. We were about leaving, when he approached his new visitor, and, with mingled gentleness and mischief, took the stick which he carried, and pretending to lean upon it, rounding his shoulders, and slackening his pace, walked round the room, imitating the figure and gait of my old friend. He then gave him back the stick of his own accord, and we took our leave, convinced that he also knew how to observe.

— M. Flourens, quoted in Ernest Menault, The Intelligence of Animals, 1869