Another decisive factor in the development of the ideal of authenticity was that it emerged together with a distinctively modern conception of the self. This is visible in the work of Rousseau, who argues that the orientation toward life that should guide the conduct one chooses should come from a source within. This led to questions about inwardness, self-reflection and introspection, many of them addressed in his Confessions (1770). When the space of interiority becomes a guiding authority, the individual must detect and distinguish central impulses, feelings and wishes from ones that are less central or conflict with one’s central motives. In other words, interiority must be divided into what is at the core and what is peripheral. In this picture, the measure of one’s actions is whether they spring from and express essential aspects of one’s identity or whether they come from a peripheral place.