Ennead VI.4-5, originally written as a single treatise, contains Plotinus' most general and sustained exposition of the relationship between the intelligible and the sensible realms, addressing and coalescing two central issues in Platonism: the nature of the soul-body relationship and the nature of participation. Its main question is, How can soul animate bodies without sharing their extension? The treatise seems to have had considerable impact: it is much reflected in Porphyry's important work, Sententiae, and the doctrine of reception according to the capacity of the recipient, for which this treatise is the main source, resonated in medieval thinkers.

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.

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.

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.

Ennead IV.4.30-45 and IV.5 retrieves the unity in this last section of Plotinus' treatise on Problems concerning the Soul. Combining translation with commentary, Gurtler enhances both the accuracy of the translation and the recovery of Plotinus' often unsuspected originality. This is especially true for IV.5, where previous translations fail to convey the concise nature of his argument against both the Aristotelian and Platonic theories of vision. Plato and Aristotle each claim that vision depends on the light between the eye and the object, but Plotinus presents evidence that this is not the case and develops a novel theory of light as a second activity that moves from source to object directly, even arguing that color is in the light itself rather than merely a quality of the object. This theory of vision, in turn, depends on the nature of sympathy developed especially in IV.4.30-45, where Plotinus shows how action at a distance is both possible and necessary for the proper unity in diversity of the sensible cosmos.

Ennead I.6 is probably the best known and most influential treatise of Plotinus, especially for Renaissance artists and thinkers. Although the title may suggest a work on aesthetics and thus of limited focus, this is far from the case. For it quickly becomes apparent that Plotinus' main interest is in transcendent beauty, which he identifies with the Good, the goal of all philosophical endeavor in the Platonist's search to assimilate himself with the divine. The treatise is at once a philosophical search for the nature of the divine and at the same time an encouragement to the individual to aspire to this goal by taking his start from the beauty which is experienced in this world; for it is an image of transcendent beauty. This upward movement of the treatise reflects throughout the speech of Socrates in Plato's Symposium in which he recounts the exhortation of the priestess Diotima to ascend from earthly to transcendent beauty, which for Plotinus is identified with the divine.

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.

A philosophical commentary on a section of the Enneads written by the last great Neoplatonist thinker, Plotinus. The treatise is entitled 'Concerning Well-Being' and was written at a late stage in Plotinus' life when he was suffering from an illness that was shortly to kill him. Its main concern is with the good man and how he should pursue the good life. The treatise is therefore central to our understanding of Plotinus' ethical theory, and the commentary seeks to explicate and elucidate that theory. Plotinus' views on how one should live in order to fulfil oneself as a human being are as relevant now as they were in the third century AD. All Greek and Latin is translated, while short summaries introducing the content of each chapter help to make Plotinus' argument clear even to the non-specialist.

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.

This interdisciplinary study of infinity explores the concept through the prism of mathematics and then offers more expansive investigations in areas beyond mathematical boundaries to reflect the broader, deeper implications of infinity for human intellectual thought. More than a dozen world-renowned researchers in the fields of mathematics, physics, cosmology, philosophy and theology offer a rich intellectual exchange among various current viewpoints, rather than displaying a static picture of accepted views on infinity. The book starts with a historical examination of the transformation of infinity from a philosophical and theological study to one dominated by mathematics. It then offers technical discussions on the understanding of mathematical infinity. Following this, the book considers the perspectives of physics and cosmology: can infinity be found in the real universe? Finally, the book returns to questions of philosophical and theological aspects of infinity.