The paper discusses one of the key concepts of Paul's anthropology, the concept of the ‘inner human being’ (όέσω άνθρωποσ). According to recent contributions by U. Duchrow, T. K. Heckel, C. Markschies and W. Burkert, Paul's concept originated in Plato. The questions still open are: How did the concept get into the hands of Paul? How does Paul interpret the concept in accordance with his own theological anthropology? Answering these two questions is the goal of the paper.