Plato

Rhema (ῥῆμα in Greek) literally means an "utterance" or "thing said" in Greek. It is a word that signifies the action of utterance.

In philosophy, it was used by both Plato and Aristotle to refer to propositions or sentences.

In linguistics, specifically the sub-field of lexical semantics, the concept of lexical innovation includes the use of neologism or new meanings (so-called semantic augmentation) in order to introduce new terms into a language's lexicon. Most commonly, this is found in technical disciplines where new concepts require names, which often takes the form of jargon. For example, in the subjects of sociology or philosophy, there is an increased technicalization in terminology in the English language for different concepts over time. Many novel terms or meanings in a language are created as a result of translation from a source language, in which certain concepts were first introduced (e.g. from Plato's Ancient Greek into Latin or from Kant's German into English).

Essentialism is the view that objects have a set of attributes that are necessary to their identity. In early Western thought, Platonic idealism held that all things have such an "essence"—an "idea" or "form". In Categories, Aristotle similarly proposed that all objects have a substance that, as George Lakoff put it, "make the thing what it is, and without which it would be not that kind of thing". The contrary view—non-essentialism—denies the need to posit such an "essence". Essentialism has been controversial from its beginning. In the Parmenides dialogue, Plato depicts Socrates questioning the notion, suggesting that if we accept the idea that every beautiful thing or just action partakes of an essence to be beautiful or just, we must also accept the "existence of separate essences for hair, mud, and dirt".

Older social theories were often conceptually essentialist. In biology and other natural sciences, essentialism provided the rationale for taxonomy at least until the time of Charles Darwin. The role and importance of essentialism in modern biology is still a matter of debate. Beliefs which posit that social identities such as race, ethnicity, nationality, or gender are essential characteristics have been central to many discriminatory or extremist ideologies. For instance, psychological essentialism is correlated with racial prejudice. Essentialist views about race have also been shown to diminish empathy when dealing with members of another racial group. In medical sciences, essentialism can lead to a reified view of identities, leading to fallacious conclusions and potentially unequal treatment.

The trivium is the lower division of the seven liberal arts and comprises grammar, logic, and rhetoric.

The trivium is implicit in De nuptiis Philologiae et Mercurii ("On the Marriage of Philology and Mercury") by Martianus Capella, but the term was not used until the Carolingian Renaissance, when it was coined in imitation of the earlier quadrivium. Grammar, logic, and rhetoric were essential to a classical education, as explained in Plato's dialogues. The three subjects together were denoted by the word trivium during the Middle Ages, but the tradition of first learning those three subjects was established in ancient Greece, by rhetoricians such as Isocrates. Contemporary iterations have taken various forms, including those found in certain British and American universities (some being part of the Classical education movement) and at the independent Oundle School in the United Kingdom.

Protagoras (/proʊˈtæɡərəs, -æs/ proh-TAG-ər-əs, -⁠ass; Ancient Greek: Πρωταγόρας) is a dialogue by Plato. The traditional subtitle (which may or may not be Plato's) is "or the Sophists". The main argument is between Socrates and the elderly Protagoras, a celebrated sophist and philosopher. The discussion takes place at the home of Callias, who is host to Protagoras while he is in town. The philosophical issues raised in the Protagoras include the unity and the teachability of virtue, and the relationship between pleasure and goodness.

Christian philosophy includes philosophies carried out by Christians or in relation to the religion of Christianity. Christian philosophy emerged with the aim of reconciling science and faith, starting from natural rational explanations with the help of Christian revelation. Several thinkers such as Origen and Augustine of Hippo believed that there was a harmonious relationship between science and faith, others such as Tertullian claimed that there was contradiction; others tried to differentiate them.

There are scholars who question the existence of a Christian philosophy itself. These claim that there is no originality in Christian thought, and its concepts and ideas are inherited from Greek philosophy. Thus, Christian philosophy would protect philosophical thought, which would already be definitively elaborated by Greek philosophy. However, Catholic scholars Philotheus Boehner and Étienne Gilson claim that Christian philosophy is not a simple repetition of ancient philosophy, although they owe to Greek science the knowledge developed by Plato, Aristotle and the Neoplatonists. They even claim that in Christian philosophy, Greek culture survives in organic form.

In his final philosophical treatise, The Passions of the Soul (French: Les Passions de l'âme), completed in 1649 and dedicated to Princess Elisabeth of Bohemia, the French philosopher and mathematician René Descartes contributes to a long tradition of philosophical inquiry into the nature of "the passions". The passions were experiences – now commonly called emotions in the modern period – that had been a subject of debate among philosophers and theologians since the time of Plato.

Notable precursors to Descartes who articulated their own theories of the passions include Augustine of Hippo, Thomas Aquinas and Thomas Hobbes.According to Amélie Rorty, the work reflects Descartes' need to reconcile the influence of the passions on otherwise rational beings. This marks a clear point in the advancement of human self-estimation, paralleling the increasingly rational-based scientific method. Descartes affirmed that the passions "are all intrinsically good, and that all we have to avoid is their misuse or their excess" (art. 211).

Reincarnation, also known as rebirth or transmigration, is the philosophical or religious concept that the non-physical essence of a living being begins a new lifespan in a different physical form or body after biological death. In most beliefs involving reincarnation, the soul of a human being is immortal and does not disperse after the physical body has perished. Upon death, the soul merely transmigrates into a newborn baby or into an animal to continue its immortality. (The term "transmigration" means the passing of a soul from one body to another after death.)

Reincarnation (punarjanman) is a central tenet of Indian religions such as Hinduism, Buddhism, Jainism, and Sikhism. In various forms, it occurs as an esoteric belief in many streams of Judaism, in certain pagan religions (including Wicca), and in some beliefs of the Indigenous peoples of the Americas and of Aboriginal Australians (though most believe in an afterlife or spirit world). Some ancient Greek historical figures, such as Pythagoras, Socrates, and Plato, expressed belief in the soul's rebirth or migration (metempsychosis).

The School of Athens (Italian: Scuola di Atene) is a fresco by the Italian Renaissance artist Raphael. It was painted between 1509 and 1511 as part of a commission by Pope Julius II to decorate the rooms now called the Stanze di Raffaello in the Apostolic Palace in Vatican City.

The fresco depicts a congregation of ancient mathematicians, philosophers, and scientists, with Plato and Aristotle featured in the center. The identities of most figures are ambiguous or discernable only through subtle details or allusions; among those commonly identified are Socrates, Pythagoras, Archimedes, Heraclitus, Averroes, and Zarathustra. Additionally, Italian artists Leonardo da Vinci and Michelangelo are believed to be portrayed through Plato and Heraclitus, respectively. Raphael included a self-portrait beside Ptolemy. Hypatia is the only notable character who is looking directly at the viewer in the artwork.

Memorabilia (original title in Ancient Greek: Ἀπομνημονεύματα, romanized: Apomnēmoneúmata) is a collection of Socratic dialogues by Xenophon (ca. 430 - 354 BC), a student of Socrates (ca. 470 – 399 BC). The lengthiest and most famous of Xenophon's Socratic writings, the Memorabilia is essentially an apologia (defense) of Socrates, differing from both Xenophon's Apology of Socrates to the Jury and Plato's Apology. Both Xenophon's and Plato's Apologies present Socrates as defending himself before the jury, whereas the Memorabilia presents Xenophon's own defense of Socrates, offering edifying examples of Socrates' conversations and activities along with occasional commentary from Xenophon. Memorabilia was particularly influential in Cynic and later Stoic philosophy.