Starting from Augustine’s definition of mens, the paper tries to demonstrate how this author forms a conception of the soul as the Trinitarian image of God through a non dualistic perspective of reality. The first section examines in which sense will, memory and intelligence can be considered different and equal faculties and what is the most important in mens as the image of God. Thereafter, the paper focuses on the Medieval controversy over the meaning of the relations between memoria-intelligentia-voluntas, emphasizing the Augustinian context from which it originated as well as some of its developments. The paper concludes the analysis of the identity of the soul with its faculties, showing how Thomas Aquinas interpreted and developped the Augustinian thought.