On the basis of the study of Petrić’s philosophy it is clear that his key theses follow the entire Neo-Platonic tradition and Plotinus’ philosophy. Plotinus’ philosophy, in view of the way it defines the relation to the ultimate principle – the One, has usually been described as a kind of mysticism in the history of philosophy. Since the links between Plotinus’ and Petrić’s philosophy of the One are incontestable, the issue regarding the presence of some elements of mysticism in Petrić’s philosophy seems to be legitimate. On the basis of the analysis of Petrić’s »new« philosophy it may be conluded that one may not speak of such an experience – which the theses on Plotinus’ mysticism in Petrić refer to – regardless of the similarity of their views concerning the transcendental qualities of the One. If we search Petrić’s philosophy for the notion approaching Plotinus’ term »henosis«, »unio«, we find it in Petrić’s concept of knowledge, defined as »coitio«, which is quite specifically conceited, defined as both gnosis and nea genesis. This concept of knowledge, based on Petrić’s philosophy of light, is closely connected with his definition of the principle – the One in the sense of the Christian doctrine concerning the Trinity explained according to the Hermetic- Chaldean tradition, in which the relation between the Mind and the One is determined according to the understanding of the relation between the Father and the Son.