When descartes thinks of his mind without a body. He means, think of yourself as a subject who"s having these theories and thoughts but does not know what the thing who"s doing the thinking is made of. He notices the concept of i does not present itself as being made of physical material; it doesn"t represent any kind of substance. Something john locke does distinguish between primary and secondary qualities. Underlying theory of perception representational model of perception. This means that information from the object goes to the subject. The eyes pick up on the object from the light then the brain sees it, thinks, and comes up with an idea. The object outside you causes ideas to arise in your mind. When he uses the term idea he says he means perception, thought and understanding connect you to an idea in your own mind .
