According to Marinus of Samaria, Proclus was the author of many philosophical doctrines. In particular he was the first to assert the existence of a kind of souls that are capable of simultaneously seeing several ideas and situated between the divine Intellect which embraces all things together by a single intuition, and the souls whose thoughts pass from one idea to another. In the following we are going to answer the question, what kind of souls did Proclus discover and why did he thought it to be necessary to introduce them in his metaphysical system. To solve this problem it seems reasonable to clarify the mechanism of horizontal-vertical progression in Proclus’ philosophy, as well as to describe the general structure of the psychic level of reality embracing the so called Monad of “unparticipated” Soul and the multiplicity if its “participated” products: divine, demonic and human souls. Unlike some previous scholars, who alleged that souls discovered by Proclus were demonic or intelligent ones, I affirm that Marinus could have in mind hypercosmic participated souls, situated between the unparticipated monad of the psychic level of reality and the multiplicity of participated souls within the material cosmos. In support of this assumption I cite some relevant passages from Proclus’ Commentary on “Timaeus” and demonstrate that he named “hypercosmic” not only the unparticipated monad of Soul, but also souls of the so called “absolute” gods, which are both in touch with the sensible cosmos and above it because of animating eternal immaterial bodies consisting of supra-celestial light. In conclusion I try to establish the genuine authorship of the doctrine of hypercosmic souls and to answer the question, why did Marinus attribute it to Proclus.