What is a person, and how can a person come to know that she is a person identical to herself over time ? The article defends the view that the sense of being oneself in this sense consists in the ability to consciously affect oneself : in the memory of having affected oneself, joint to the consciousness of being able to affect oneself again. In other words, being a self requires a capacity for metacognition (control and monitoring of one's own internal states). This view is compatible with the hypothesis that the self is a dynamic representation emerging out of a higher level control system, - valuation control - whose articulation with control of plans and perceptual/motor control is discussed in the context of normal and pertrubed agency...