Aspiration by Agnes Callard locates standing assumptions in the theory of rationality, moral psychology and autonomy that preclude the possibility of working to acquire new values. The book also explains what changes need to be made if we are to make room for this form of agency, which I call aspiration. A superb, agenda-setting addition to recent philosophical investigations into 'transformative experience', the kind of experience that results in changes to one's basic values. Callard rightly singles out "aspiration" a change in one's values that, she argues, is rationally guided by what those values will become as a critically important species of such experience, and brings out, with clarity, insight, and brilliance, the deep connections between this phenomenon and a range of other central topics in moral psychology and the theory of practical reasoning, such as the nature of moral responsibility, internalism about reasons, and akrasia.