Now two things are requisite to our complete and more pleasurable perception of this: first, that the resemblance be so perfect as to amount to a deception; secondly, that there be some means of proving at the same moment that it is a deception. The most perfect ideas and pleasures of imitation are, therefore, when one sense is contradicted by another, both bearing as positive evidence on the subject as each is capable of alone; as when the eye says a thing is round, and the finger says it is flat