Question: What word is both the name of Euphronius of the Athenian dem Sunium's son and is also one of Plato's diaglogues concerning the nature of knowledge?

The analogy of the sun (or simile of the sun or metaphor of the sun) is found in the sixth book of "The Republic" (507b–509c), written by the Greek philosopher Plato as a dialogue between Glaucon (Plato's elder brother) and Socrates (narrated by the latter).  Upon being urged by Glaucon to define goodness, a cautious Socrates professes himself incapable of doing so.  Instead he draws an analogy and offers to talk about "the child of goodness" (Greek: "ἔκγονός τε τοῦ ἀγαθοῦ" ).  Socrates reveals this "child of goodness" to be the sun, proposing that just as the sun illuminates, bestowing the ability to see and be seen by the eye, with its light so the idea of goodness illumines the intelligible with truth.  While the analogy sets forth both epistemological and ontological theories, it is debated whether these are most authentic to the teaching of Socrates or its later interpretations by Plato.  The sun is a metaphor for the nature of reality and knowledge concerning it. <SEP> Thomistic sacramental theology is St. Thomas Aquinas's theology of the sacraments of the Catholic Church.  It can be found through his writings in the "Summa contra Gentiles" and in the "Summa Theologiæ".  As can be seen, Aquinas relied heavily on Scriptural passages, as well as the writings of various Church Fathers.  St. Augustine says (De Civ.  Dei x): The visible sacrifice is the sacrament.  This is the sacred sign of the invisible sacrifice.  A thing is called a sacrament, either by having a certain hidden sanctity, and in this sense a sacrament is a sacred secret; or from having some relationship to this sanctity.  A sacrament is a sign.  Moreover, it is a sacred sign.  Divine Wisdom provides for each thing according to its mode.  Wisdom 7,1 : "she... ordered all things sweetly"; and from Matthew 25,15: "[she] gave to everyone according to his proper ability."  It is a part of human nature to acquire knowledge of the intelligible from the sensible.  A sign is the way one obtains knowledge of something else.  The sacraments are the signs by which humans gain knowledge of spiritual and intelligible goods.  Ephesians 5, 25-26: "Christ loved the Church, and delivered Himself up for it; that He might sanctify it, cleansing it by the laver of water in the word of life."  St. Augustine says (Tract.  xxx in John): "The word is added to the element, and this becomes the sacrament."  Augustine (Contra Faust xix): "It is impossible to keep men together in one religious denomination, whether true or false, except they be united by means of visible signs or sacraments."  It is necessary for salvation that humans united together in the name of true religion.  Therefore, sacraments are necessary for man's salvation.  There are three reasons sacraments are necessary to the salvation of humans: First, it is in the nature of humans to be led by things corporal and sensible to things that are spiritual and intelligible.  Second, by sinning, humans have subjected themselves to corporeal things.  Therefore, it is proper that the remedy have a corporeal side, leading to the spiritual.  Third, humans are prone to direct their activity towards material things (things that can be seen and felt).  Sacraments are made necessary because humans have sinned.  The main effect of the sacraments is grace, in particular those involving Virtues and Gifts.  Grace perfects the soul and allow participation in the Divine Nature.  Furthermore, the effects of the sacraments is justification.  This is an interior effect.  Romans 8,33: "God justifies."  Therefore, the effects of the sacraments is justification.  This is an interior effect.  The power of the sacraments is from God, alone.  It does not matter that the minister of the sacraments may be a sinner, or evil.  Augustine (commenting on John 1,33): "He upon Whom you shall see the Spirit, ...that John did not know that our Lord, having the authority of baptizing, would keep it to Himself, but that the ministry would certainly pass to both good and evil men...What is a bad minister to you, wherever the Lord is good?" <SEP> The Theaetetus ( ; Greek: Θεαίτητος ) is one of Plato's dialogues concerning the nature of knowledge, written "circa" 369 BC. <SEP>  His principal contributions were on irrational lengths, which was included in "Book X" of Euclid's "Elements", and proving that there are precisely five regular convex polyhedra. Theaetetus of Athens ( ; Greek: Θεαίτητος ; c. 417 – 368 BC), possibly the son of Euphronius of the Athenian deme Sunium, was a Greek mathematician.  A friend of Socrates and Plato, he is the central character in Plato's eponymous Socratic dialogue.