Plotinus (ca. CE 204/5–270) was a major philosopher

Philosophy

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

 of the ancient world. In his system of theory there are the three principles: the One, the Intellect, and the Soul. His teacher was Ammonius Saccas

Ammonius Saccas

Ammonius Saccas was a Greek philosopher from Alexandria who was often referred to as one of the founders of Neoplatonism. He is mainly known as the teacher of Plotinus, whom he taught for eleven years from 232 to 243. He was undoubtably the biggest influence on Plotinus in his development of...

 and he is of the Platonic tradition. Historians of the 19th century invented the term Neoplatonism

Neoplatonism

Neoplatonism , is the modern term for a school of religious and mystical philosophy that took shape in the 3rd century AD, based on the teachings of Plato and earlier Platonists, with its earliest contributor believed to be Plotinus, and his teacher Ammonius Saccas...

and applied it to him and his philosophy which was influential in Late Antiquity

Late Antiquity

Late Antiquity is a periodization used by historians to describe the time of transition from Classical Antiquity to the Middle Ages, in both mainland Europe and the Mediterranean world. Precise boundaries for the period are a matter of debate, but noted historian of the period Peter Brown proposed...

. Much of the biographical information about Plotinus comes from Porphyry

Porphyry (philosopher)

Porphyry of Tyre , Porphyrios, AD 234–c. 305) was a Neoplatonic philosopher who was born in Tyre. He edited and published the Enneads, the only collection of the work of his teacher Plotinus. He also wrote many works himself on a wide variety of topics...

's preface to his edition of Plotinus' Enneads

Enneads

The Six Enneads, sometimes abbreviated to The Enneads or Enneads , is the collection of writings of Plotinus, edited and compiled by his student Porphyry . Plotinus was a student of Ammonius Saccas and they were founders of Neoplatonism...

.