 Ideas are not the only modes of thinking. Doubting and judging, for example, are also modes of thinking. Early in the Third Meditation, Descartes works out a basic division of the various modes of thinking. He sorts them into two kinds: simple and complex. Ideas are included in the category of simple modes. Doubting, judging, and the like, are included in the category of complex modes. Even so, all complex modes include ideas as constituents. A complex mode of thought includes at least two basic mental components: an idea and some “additional” mental feature. He writes: