The term ‘Neoplatonism’ is a modern construction. Plotinus, who is often considered the ‘founder’ of Neoplatonism, would not have considered himself a “new” Platonist in any sense, but simply an expositor of the doctrines of Plato. That this required him to formulate an entirely new philosophical system would not have been viewed by him as a problem, for it was, in his eyes, precisely what the Platonic doctrine required.
In a sense, this is true, for as early as the Old Academy we find Plato’s successors struggling with the proper interpretation of his thought, and arriving at strikingly different conclusions. Also, in the Hellenistic era, certain Platonic ideas were taken up by thinkers of various loyalties — Jewish, Gnostic, Christian — and worked up into new forms of expression that varied quite considerably from what Plato actually wrote in his Dialogues. Should this lead us to the conclusion that these thinkers were any less ‘loyal’ to Plato than were the members of the Academy (in its various forms throughout the centuries preceding Plotinus)? No; for the multiple and often contradictory uses made of Platonic ideas is a testament to the universality of Plato’s thought — that is, its ability to admit of a wide variety of interpretations and applications.
In this sense, Neo-Platonism may be said to have begun immediately after Plato’s death, when new approaches to his philosophy were being broached. Indeed, we already see a hint, in the doctrines of Xenocrates (the second head of the Old Academy) of a type of salvation theory involving the unification of the two parts of the human soul — the “Olympian” or heavenly, and the “Titanic” or earthly (Dillon 1977, p. 27). If we accept Frederick Copleston’s description of Neoplatonism as “the intellectualist reply to the … yearning for personal salvation” (Copleston 1962, p. 216) we can already locate the beginning of this reply as far back as the Old Academy, and Neoplatonism would then not have begun with Plotinus. However, it is not clear that Xenocrates’ idea of salvation involved the individual; it is quite possible that he was referring to a unified human nature in an abstract sense.
In any case, the early Hermetic-Gnostic tradition is certainly to an extent Platonic, and later Gnosticism and Christian Logos theology markedly so. If an intellectual reply to a general yearning for personal salvation is what characterizes Neoplatonism, then the highly intellectual Gnostics and Christians of the Late Hellenistic era must be given the title of Neoplatonists. However, if we are to be rigorous and define Neoplatonism as the synthesis of various more or less ‘Platonistic’ ideas into a grand expression of Platonic philosophy, then Plotinus must be considered the founder of Neoplatonism. Yet we must not forget that these Platonizing Christian, Gnostic, Jewish, and other ‘pagan’ thinkers provided the necessary speculative material to make this synthesis possible."