Plotinus (205-270): Greek philosopher, creator of the great synthesis of late Antiquity, called Neo-Platonism.
After the age of Posidonius of Apamea, it was not uncommon that philosophers from one school borrowed concepts and ideas from other branches of philosophy. Slowly, the schools were merging, and a new synthesis (called Neo-Platonism) was created by Plotinus (205-270).
Like Plato, Plotinus accepted that our world was a mere shadow of the world of the ideas, which was in turn -and this was a novel idea- a shadow of an even higher world, which was again a shadow of the One God. In other words, the world has four levels of reality: God was the highest level, and then there were the levels of the intellect, the soul, and matter. (That matter is more real than the speculative levels of existence, as we think, was an unusual idea in Antiquity.)
According to Plotinus, the wise man would try, by means of ascesis, to free his soul from matter and unite it with God. Plotinus achieved this unity several times, and it would not be wrong to compare him to the mystics of all civilizations.
His pupil Porphyrius organized the treatises of Plotinus (the Enneads) and also wrote a biography of his master. The Neo-Platonic philosophy was adopted by the fathers of the church Ambrose and Augustine, and was to remain the philosophical school par excellence until Aristotle of Stagira was rediscovered in the twelfth century.