What writings of Plotinus were collected in the Enneads?

The writings of the ancient philosopher Plotinus were collected and arranged by his disciple Porphyry into a work known as the Enneads.12

The title Enneads is derived from the Greek word enneas, meaning "set of nine," as the collection consists of six sets of nine treatises each. Plotinus wrote these individual treatises for his circle of friends and collaborators in Rome, which included Porphyry, Amelius Gentilianus, and his physician, Eustochius. These writings serve as the foundational texts of Neoplatonism, detailing his philosophical system regarding the One, the Intellect, and the Soul, as well as his views on the nature of the universe and the human path toward mystical union with the Good.21