The term dunamis (potentiality) entered into the philosophical vocabulary with Plato, but it was with Aristotle that it acquired, together with energeia (actuality), the strong technical meaning that the two terms have maintained, with variations, throughout subsequent philosophical tradition. The significance of the notions of actuality and potentiality in Plotinus' thought can hardly be overstated. Throughout the Enneads, they are crucial to understanding the specific causality of intelligible realities and the relation of participation between intelligible and sensible realms. In Ennead II.5, Plotinus for the first time provides a systematic clarification of his peculiar use of these terms, through a sustained revision of Aristotle's own elaboration of the topic and of his terminology. The treatise discusses the different meanings of potentiality and actuality as well as the way each of them applies or does not apply to the sensible realm, to the intelligible realm, and to matter.

Platonists beginning in the Old Academy itself and up to and including Plotinus struggled to understand and articulate the relation between Plato's Demiurge and the Living Animal which served as the model for creation. The central question is whether "e;contents"e; of the Living Animal, the Forms, are internal to the mind of the Demiurge or external and independent. For Plotinus, the solution depends heavily on how the Intellect that is the Demiurge and the Forms or intelligibles are to be understood in relation to the first principle of all, the One or the Good. The treatise V.5 [32] sets out the case for the internality of Forms and argues for the necessary existence of an absolutely simple and transcendent first principle of all, the One or the Good. Not only Intellect and the Forms, but everything else depends on this principle for their being.

On Our Allotted Guardian Spirit is a lively and at times perplexing text combining general reflections on the nature of the soul with a discussion of the phenomenon of a personal guardian spirit. Plotinus wants to interpret Plato, and aims to integrate Plato's various statements about daimones into one comprehensive theory. This leads to some views that are, if not exotic, then at least strange on first encounter. However, a closer reading reveals that Plotinus is not interested in demonology per se. Instead, the central concern of the treatise are ideas about the soul, the self, and self-consciousness. Plotinus' explorations produce a theory of the mind as the agent and activity responsible for a person’s ethical choices and conduct of life. The demon emerges as a philosophical tool passed down from Plato, but adapted and rationalized to try to explain motivation to action, the impulse toward the ethical life, and even the various differences in human ethical and psychological constitution. This innovative theory is a response to a strong and ongoing current of thought in the philosophical tradition. The introduction offers an overview of ancient demonologies, starting with Homer and the Presocratics, and is followed by an in-depth examination of Plato, the Stoics, Plotinus, and later Neoplatonic developments. As such the book presents Plotinus’ specific rationalizing response to the idea of a guardian spirit in the context of ancient philosophical demonologies.

Ennead IV.7 is a very early treatise (second according to Porphyry's chronological table), and unlike the many treatises devoted to attempts at untangling various issues Plotinus found problematic in Plato's thinking, this one presents the teachings of the other main schools current in Plotinus' day: the Stoics, Epicureans, Pythagoreans, and Peripatetics, all of whom presented soul as something material or as contingent upon material soul, and so as being neither truly immortal nor imperishable. It includes observations on many mainly Stoic doctrines on perception, memory, sensation, thought, virtue, powers of material bodies, mixture and reproduction (Chapters 1-83); on Pythagorean attunement (84); and on Peripatetic entelechy (85). In Chapters 9-10 Plotinus presents, in broad terms, Plato's doctrines on soul's immortality-mainly that of the individual soul, but a fortiori that of the soul of the cosmos. These chapters offer some of Plotinus' most powerful prose. He is not concerned to prove the soul's immortality-that was an uncontroversial tenet of Platonism, to be taken for granted. In this treatise Plotinus is laying down the indisputable foundations for his later writings.

The first book-length philosophical study on the Presocratic influences in Plotinus’ Enneads.

Ennead I.1 is a succinct and concentrated analysis of key themes in Plotinus' psychology and ethics. It focuses on the soul-body relation, discussing various Platonic, Aristotelian, and Stoic views before arguing that there is only a soul-trace in the body (forming with the body a "e;compound"e;), while the reasoning soul itself is impassive and flawless. The soul-trace hypothesis is used to account for human emotions, beliefs, and perceptions, and human fallibility in general. Its problematic relation to our rational powers, as well as the question of moral responsibility, are explored. Plotinus develops his original and characteristic concept of the self or "e;we,"e; which is so called because it is investigated as something common to all humans (rather than a private individual self), and because it is multiple, referring to the reasoning soul or to the "e;living thing"e; composed of soul-trace and body. Plotinus explores the relation between the "e;we"e; and consciousness, and also its relation to the higher metaphysical entities, the Good, and Intellect.

Ennead VI.8 gives us access to the living mind of a long dead sage as he tries to answer some of the most fundamental questions we in the modern world continue to ask: are we really free when most of the time we are overwhelmed by compulsions, addictions, and necessities, and how can we know that we are free? Can we trace this freedom through our own agency to the gods, to the Soul, Intellect, and the Good? How do we know that the world is meaningful and not simply the result of chance or randomness? Plotinus' On the Voluntary and on the Free Will of the One is a groundbreaking work that provides a new understanding of the importance and nature of free human agency. It articulates a creative idea of agency and radical freedom by showing how such terms as desire, will, self-dependence, and freedom in the human ethical sphere can be genuinely applied to Intellect and the One while preserving the radical inability of all metaphysical language to express anything about God or gods.

How was the universe created, and what is our place within it? These are the questions at the heart of Plotinus' Against the Gnostics. For the Gnostics, the universe came into being as a result of the soul's fall from intelligible reality-it is the evil outcome of a botched creation. Plotinus challenges this, and insists that the soul's creation of the world is the necessary consequence of its contemplation of the ideal forms. While the Gnostics claim to despise the visible universe, Plotinus argues that such contempt displays their ignorance of the higher realities of which the cosmos is a beautiful image.

This study offers an innovative understanding of the central role of the act of contemplation in the philosophy of Plotinus.

Plotinus' Treatise V.1 comes closer than any other to providing an outline of his entire spiritual and metaphysical system, and as such it may serve to some degree as an introduction to his philosophy. It addresses in condensed form a great many topics to which Plotinus elsewhere devotes extended discussion, including the problem of the multiple self; eternity and time; the unity-in-duality of intellect and the intelligible; and the derivation of intelligible being from the One. Above all, it shows that the so-called "e;three hypostases"e;-soul, intellect, and the One-are best understood not as a sequence of three things additional to one another, but as three levels of possession of the same content, so that each lower level-soul in relation to intellect and intellect in relation to the One-is an "e;image"e; and "e;expression"e; of its superior. Plotinus exhorts the human soul to overcome its alienation from its own true nature and its divine origin by first recognizing itself as superior to the body and the same in kind as the animating principle of the entire cosmos, and then discovering within itself the still higher levels of reality from which it derives: intellect and, ultimately, the One or Good, the supreme first principle of all things. To do so the soul must redirect its attention inward and upward to become aware of the divinity which is always within it but from which it is distracted by the clamor of the senses.