So far the meditator has established a good deal about the nature of his own mind, and he has also secured the c&d rule by demonstrating that god exists and cannot be a deceiver. His next priority is to see if anything certain is to be had concerning material things (45). But before he considers whether any material objects exist in the world, he first considers his idea or concept of extension. He finds that he knows quite a lot about the nature of material objects that holds true regardless of whether any such things exist. Our ideas of things with true and immutable natures are innate, and our knowledge of these things is a priori (independent of experience). Ultimately, then, we can know quite a lot regarding the essence of material things without ever consulting sense experience. These considerations then prompt the meditator to consider another argument for god"s existence.
