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🔗 History 🔗 Middle Ages 🔗 Middle Ages/History

The Nine Worthies are nine historical, scriptural, and legendary personages who personify the ideals of chivalry established in the Middle Ages, whose lives were deemed a valuable study for aspirants to chivalric status. All were commonly referred to as 'Princes', regardless of their historical titles. In French they are called Les Neuf Preux or "Nine Valiants", giving a more specific idea of the moral virtues they exemplified: those of soldierly courage and generalship. In Italy they are i Nove Prodi.

The Nine Worthies include three pagans (Hector, Alexander the Great and Julius Caesar), three Jews (Joshua, David and Judas Maccabeus) and three Christians (King Arthur, Charlemagne and Godfrey of Bouillon).

Polanyi’s paradox, named in honour of the British-Hungarian philosopher Michael Polanyi, is the theory that human knowledge of how the world functions and capability are, to a large extent, beyond our explicit understanding. The theory was articulated by Michael Polanyi in his book The Tacit Dimension in 1966, but it was economist David Autor that named it as Polanyi’s paradox in his 2014 research paper on “Polanyi’s Paradox and the Shape of Employment Growth”.

Summarised in the slogan "We can know more than we can tell", Polanyi’s paradox is mainly to explain the cognitive phenomenon that there exist many tasks which we, human beings, understand intuitively how to perform but cannot verbalize the rules or procedures behind it. This "self-ignorance" is common to many human activities, from driving a car in traffic to face recognition. As Polanyi argues, humans are relying on their tacit knowledge, which is difficult to adequately express by verbal means, when engaging these tasks. Polanyi's paradox has been widely considered a major obstacle in the fields of AI and automation, since the absence of consciously accessible knowledge creates tremendous difficulty in programming.

🔗 Philosophy 🔗 Philosophy/Philosophical literature 🔗 Books 🔗 Philosophy/Modern philosophy 🔗 Japan 🔗 Philosophy/Eastern philosophy

The "Dokkōdō" (Japanese: 獨行道) ("The Path of Aloneness", "The Way to Go Forth Alone", or "The Way of Walking Alone"), is a short work written by Miyamoto Musashi a week before he died in 1645. It consists of 21 precepts. "Dokkodo" was largely composed on the occasion of Musashi giving away his possessions in preparation for death, and was dedicated to his favorite disciple, Terao Magonojō (to whom the earlier Go rin no sho [The Book of Five Rings] had also been dedicated), who took them to heart. "Dokkōdō" expresses a stringent, honest, and ascetic view of life.

The 21 precepts of Dokkodo:

1. Accept everything just the way it is.

2. Do not seek pleasure for its own sake.

3. Do not, under any circumstances, depend on a partial feeling.

4. Think lightly of yourself and deeply of the world.

5. Be detached from desire your whole life long.

6. Do not regret what you have done.

7. Never be jealous.

8. Never let yourself be saddened by a separation.

9. Resentment and complaint are appropriate neither for oneself or others.

10. Do not let yourself be guided by the feeling of lust or love.

11. In all things have no preferences.

12. Be indifferent to where you live.

13. Do not pursue the taste of good food.

14. Do not hold on to possessions you no longer need.

15. Do not act following customary beliefs.

16. Do not collect weapons or practice with weapons beyond what is useful.

17. Do not fear death.

18. Do not seek to possess either goods or fiefs for your old age.

19. Respect Buddha and the gods without counting on their help.

20. You may abandon your own body but you must preserve your honour.

21. Never stray from the Way.

🔗 Medicine

The choking game (also known as the fainting game and a wide variety of slang terms) refers to intentionally cutting off oxygen to the brain with the goal of inducing temporary loss of consciousness and euphoria.

🔗 Skepticism 🔗 Zimbabwe 🔗 Paranormal 🔗 Folklore

On September 16, 1994, there was a UFO sighting outside Ruwa, Zimbabwe. 62 students at the Ariel School aged between six and twelve claimed that they saw one or more silver craft descend from the sky and land on a field near their school. One or more creatures dressed all in black then approached the children and telepathically communicated to them a message with an environmental theme.

The Fortean writer Jerome Clark has called the incident the “most remarkable close encounter of the third kind of the 1990s”. Skeptics have described the incident as one of mass hysteria. Not all the children at the school that day claimed that they saw something. Several of those that did maintain that their account of the incident is true.

🔗 Books 🔗 Middle Ages 🔗 Middle Ages/History 🔗 Visual arts

The Black Hours, MS M.493 (or the Morgan Black Hours) is an illuminated book of hours completed in Bruges between 1460 and 1475. It consists of 121 pages (leaves), with Latin text written in Gothic minuscule script. The words are arranged in rows of fourteen lines and follow the Roman version of the texts. The lettering is inscribed in silver and gold and placed within borders ornamented with flowers, foliage and grotesques, on pages dyed a deep blueish black. It contains fourteen full-page miniatures and opens with the months of the liturgical calendar (folios 3 verso – 14 recto), followed by the Hours of the Virgin, and ends with the Office of the Dead (folio 121v).

MS M.493 has been in the collection of the Morgan Library & Museum, New York, since 1912. It is one of seven surviving black books of hours, all originating from Bruges and dated to the mid-to-late 15th century. They are so named for their unusual dark blueish appearance, a colourisation achieved through the expensive process of dyeing the vellum with iron gall ink. This dye is very corrosive and the surviving examples are mostly badly decomposed; MS M.493 is in relatively good condition due to its very thick parchment.

The book is a masterpiece of Late Gothic manuscript illumination. However, no records survive of its commission, but its uniquely dark tone, expense of production, quality and rarity suggest ownership by privileged and sophisticated members of the Burgundian court. The book is often attributed, on stylistic grounds, to a follower of Willem Vrelant, a leading and influential Flemish illuminator.

🔗 Medicine 🔗 Biology

The blue field entoptic phenomenon is an entoptic phenomenon characterized by the appearance of tiny bright dots (nicknamed blue-sky sprites) moving quickly along undulating pathways in the visual field, especially when looking into bright blue light such as the sky. The dots are short-lived, visible for about one second or less, and traveling short distances along seemingly random, undulating paths. Some of them seem to follow the same path as other dots before them. The dots may appear elongated along the path, like tiny worms. The dots' rate of travel appears to vary in synchrony with the heartbeat: they briefly accelerate at each beat. The dots appear in the central field of view, within 15 degrees from the fixation point. The left and right eye see different, seemingly random, dot patterns; a person viewing through both eyes sees a combination of both left and right visual field disturbances. While seeing the phenomenon, lightly pressing inward on the sides of the eyeballs at the lateral canthus causes the movement to stop being fluid and the dots to move only when the heart beats.

Most people are able to see this phenomenon in the sky, although it is relatively weak in most instances; many will not notice it until asked to pay attention. The dots are highly conspicuous against any monochromatic blue background of a wavelength of around 430 nm in place of the sky. The phenomenon is also known as Scheerer's phenomenon, after the German ophthalmologist Richard Scheerer, who first drew clinical attention to it in 1924.

🔗 Mathematics

This is a list of mathematical symbols used in all branches of mathematics to express a formula or to represent a constant.

A mathematical concept is independent of the symbol chosen to represent it. For many of the symbols below, the symbol is usually synonymous with the corresponding concept (ultimately an arbitrary choice made as a result of the cumulative history of mathematics), but in some situations, a different convention may be used. For example, depending on context, the triple bar "≡" may represent congruence or a definition. However, in mathematical logic, numerical equality is sometimes represented by "≡" instead of "=", with the latter representing equality of well-formed formulas. In short, convention dictates the meaning.

Each symbol is shown both in HTML, whose display depends on the browser's access to an appropriate font installed on the particular device, and typeset as an image using TeX.