 The dispute between rationalism and empiricism takes place primarily within epistemology, the branch of philosophy devoted to studying the nature, sources, and limits of knowledge. Knowledge itself can be of many different things and is usually divided among three main categories: knowledge of the external world, knowledge of the internal world or self-knowledge, and knowledge of moral and/or aesthetical values. We may find that there are category-specific conditions that must be satisfied for knowledge to occur and that it is easier or more difficult to shape certain questions and answers, depending on whether we focus on the external world or on the values. However, some of the defining questions of general epistemology include the following.