Phaedo in the context of "The Death of Socrates"

Platonism is the philosophy of Plato and philosophical systems closely derived from it, though later and contemporary Platonists do not necessarily accept all of Plato's own doctrines. Platonism has had a profound effect on Western thought. At the most fundamental level, Platonism affirms the existence of abstract objects, which are asserted to exist in a third realm distinct from both the sensible external world and from the internal world of consciousness, and is the opposite of nominalism. This can apply to properties, types, propositions, meanings, numbers, sets, truth values, and so on (see abstract object theory). Philosophers who affirm the existence of abstract objects are sometimes called Platonists; those who deny their existence are sometimes called nominalists. The terms "Platonism" and "nominalism" also have established senses in the history of philosophy. They denote positions that have little to do with the modern notion of an abstract object.

In a narrower sense, the term might indicate the doctrine of Platonic realism, a form of mysticism. The central concept of Platonism, a distinction essential to the Theory of Forms, is the distinction between the reality which is perceptible but unintelligible, associated with the flux of Heraclitus and studied by the likes of physical science, and the reality which is imperceptible but intelligible, associated with the unchanging being of Parmenides and studied by the likes of mathematics. Geometry was the main motivation of Plato, and this also shows the influence of Pythagoras. The Forms are typically described in dialogues such as the Phaedo, Symposium and Republic as perfect archetypes of which objects in the everyday world are imperfect copies. Aristotle's Third Man Argument is its most famous criticism in antiquity.

Ammonius Hermiae (/əˈmoʊniəs/; Ancient Greek: Ἀμμώνιος ὁ Ἑρμείου, romanized: Ammōnios ho Hermeiou, lit. 'Ammonius, son of Hermias'; c. 440 – between 517 and 526) was a Greek philosopher from Alexandria in the eastern Roman empire during Late Antiquity. A Neoplatonist, he was the son of the philosophers Hermias and Aedesia, the brother of Heliodorus of Alexandria and the grandson of Syrianus. Ammonius was a pupil of Proclus in Roman Athens, and taught at Alexandria for most of his life, having obtained a public chair in the 470s.

According to Olympiodorus of Thebes's Commentaries on Plato's Gorgias and Phaedo texts, Ammonius gave lectures on the works of Plato, Aristotle, and Porphyry of Tyre, and wrote commentaries on Aristotelian works and three lost commentaries on Platonic texts. He is also the author of a text on the astrolabe published in the Catalogus Codicum Astrologorum Graecorum, and lectured on astronomy and geometry. Ammonius taught numerous Neoplatonists, including Damascius, Olympiodorus of Thebes, John Philoponus, Simplicius of Cilicia, and Asclepius of Tralles. Also among his pupils were the physician Gessius of Petra and the ecclesiastical historian Zacharias Rhetor, who became the bishop of Mytilene.

Simmias of Thebes (Ancient Greek: Σιμμίας Θηβαῖος; fl. 5th–4th century BC) was an ancient Greek philosopher, disciple of Socrates, and a friend of Cebes. In his Memorabilia, Xenophon includes him in the inner circle of Socrates' followers. He appears in Plato's Phaedo as a main discussion partner of Socrates alongside Cebes, as well as Crito, Phaedrus, and Epistle XIII.

In addition to the references in Plato and Xenophon, Diogenes Laërtius mentions Simmias as the author of 23 brief dialogues, now lost, including On Philosophy and On Music. Simmias appears as a character in Plutarch's De Genio Socratis section of the Moralia. A pseudepigraphic letter from Xenophon to Simmias and Cebes is included in the Cynic epistles attributed to Socrates' followers. Two short works are also attributed to him in the Greek Anthology, a couplet on Sophocles and an epitaph on Plato.

Euenus (or Evenus) of Paros, (Greek: Εὔηνος ὁ Πάριος), was a 5th-century BC poet who was roughly contemporary with Socrates.

Euenus is mentioned several times in Plato's Phaedo, Phaedrus, and Apology of Socrates. According to Maximus Tyre, Evenus was the instructor of Socrates in poetry, a statement which derives some countenance from a passage in Plato from which it may also be inferred that Euenus was alive at the time of Socrates's death, but at such an advanced age that he was likely soon to follow him. Eusebius places him at the 30th Olympiad (B. C. 460) and onwards. His poetry was gnomic, that is, it formed the vehicle for expressing philosophic maxims and opinions. The first six of the epigrams in the Greek Anthology which bear the name "Euenus" are of this character, and may therefore be ascribed to him with tolerable certainty. Perhaps, too, the fifteenth should be assigned to him.