Plotinus' treatise against the contemporary Gnosis (II 9) is a well known part of his anti-gnostic tetralogy. The basic documents of the relationship of the two systems of thought are the apologetic work of Plotinus and some writings from the Coptic Gnostic Library. Most gnostic ideas derived from Plato's own thoughts. Plotinus' philosophy and the gnostic tracts have some aspects in common to demonstrate the interactions between the gnostics and the metaphysical conception of the Middle and Neo-Platonism. One part of the gnostic writings is the Sethian Texts: 'Allogenes' (NHC XI, 3), 'Marsanes' (NHC X, 1), 'Zostrianos' (NHC VIII, 1) and the 'Three Steles of Seth' (NHC VII, 5). These treatises describe the visionary contemplative ascension to the highest Unknowable One. In the plotinian and gnostic models the parallels are first of all between the same terminology of negative ('apophatic') theology in the descriptions of the first principle, second, the nous and ennoia ('Barbelo') as the second noetic faculty (with the noetic triad of the Life, Being, Mind), third, the noetic kosmos and the pleroma, and finally the speculations of the ascension. The gnostic despise of the Creator and of the world was the main point of their discussion. The most significant and unique sign of the gnostic Demiurge is its negative characterization and criticism, which is outstanding in the Late Antiquity. According to the gnostic opinion the evil Creator of the imperfect cosmos who keeps men in the bonds of ignorance could be analysed as a literal reading of the Platonic concept of the world's Maker. The middle-platonist Numenius, Plotinus and the author of the 'Poimandres' all used the motif of fire as an emblematic description of the mediatory process of knowledge. The gnostic Wisdom myth is an explanation of the personified Sophia, the deficiency of the femaleness. The gnostic despise of the Creator and of the World could be the consequence of the wrong contemplation of Sophia, from which the Creator originated. The personified Plane and this failure caused the world.