The reason for this confusion between body and matter is due, says Cordemoy, to an over-reliance on the senses: “we have a very clear idea of body, and as we know that they are extended substances, without thinking clearly we join this notion which we have of body to that which we have of matter. Taking a mass for a body, we consider it as a substance, believing that all that we see is only the same extension. And because all that we see as extended is divisible, we thus join the notion of that