Meditations - pg. 79

The chief problem is about the ideas that I regarded as taken from external objects. What is my motive for thinking them similar to those objects? Nature seems to have taught me. Moreover, I find they do not depend o my will, or upon myself; I often get them even if I do not wish; for instance, I now feel heat willy-nilly, and so think this sensation or idea of heat comes to me from an object other than myself -- from the heat of the fire I am sitting over. And nothing appears more obvious than the judgment that what the object implants in me is its own likeness rather than something else.