Saint Augustine is sometimes introduced as the first theologian-philosopher, a founder of the Western theologico-philosophical tradition, and a figure who unites two historical times—the Late Antiquity with the Middle Ages—and two different major schools—the Hellenistic philosophy with Christianity. Augustine lives and writes in the era of eudaimonism, teleology and virtue ethics, and he accomplishes, as we will see, a clear shift in the context of these doctrines. In this paper, we reconstruct Augustine’s philosophical approach to human psychology, looking at the (...) elements that bring together a philosophical anthropology, especially by focusing on human agency. Through an interpretative study of De libero arbitrio, we will address concepts such as the soul, freedom of choice, virtue, justice, faith and knowledge, seen as components of action, human freedom, intellect and the will. My main claim is that Augustinian thought and medieval philosophy generally can still offer arguments in practical philosophy as much as they can promote our understanding of moral agency. I intend to revive the interest both in this particular Augustinian work and in the forgotten concept of liberum arbitrium that is introduced and represents Augustine’s idea of a mediator, an arbitrator between reason and the will. (shrink)