 Diderot expresses his materialism in this work through the character of a blind man, also because he is like a living counterexample to the argument from design. Indeed, Saunderson says to his interlocutor, who is defending physico-theological design and order: “What did we do to God, you and I, so that one of us possesses this organ (of sight), and the other of us is deprived of it?” (DPV IV: 63). In a further twist, Diderot also equates the blind man with idealist metaphysics since it is also cut off from direct sensory engagement with the world. Here, empiricism is no longer just a doctrine about the sources of knowledge, i.e., an epistemology. The world of a blind man is different from that of a deaf man, and so forth. Further, an individual who possessed a sense in addition to our five senses would find our ethical horizon quite imperfect (DPV IV: 27).