In Avicenna's Nafs there are two investigations that run in parallel from its very beginning: (a) the investigation of the soul as a relational entity, always considered in connection with the body, and (b) that of the human soul in itself. Both investigations aim at ascertaining the existence and the essence of the soul, in relation to the body, of which it is the soul, and in itself respectively. The aim of this contribution is to reconstruct the phases of these investigations, in order to single out the way in which they are mutually related to each other, and to detect what acts as an indicator of the transition from the first, more general investigation to the second, more specific one. In my reconstruction, this role is assigned to the Flying Man experiment. In order to corroborate this interpretation, passages from three other Avicennian works (Ḥikma mašriqiyya or al-Mašriqiyyūn, Kitāb al-Išārāt wa-l-Tanbīhāt, and Risāla Aḍḥawiyya fī l-ma‘ād) are taken into account, since they contain the three other attested formulations of the Flying Man experiment, and an argumentative move similar to the one detectable in the Nafs.