To try to prove his existence, Descartes first begins with the doctrine of ideas. Which mainly reveals our nature as thinking things are thoughts. However, these thoughts are divided into categories. One of the categories is what you think about and the other is how you think. The category about what you think about is mostly just about plans, images, feelings, and emotions. The most complex category is that of the way we think since it is divided into subcategories: understanding, wanting and imagining. Descartes then deduces that if he has an idea, then that idea must therefore exist at least in ideas, not necessarily as mind-independent