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Posts Tagged ‘House of Wisdom

“See the turtle of enormous girth, on his shell he holds the earth”*…

An illustration of the “Hindu Earth” from 1876

On the roots of a surprisingly wide-spread– and durable– image…

Anyone who’s ever heard the expression “it’s turtles all the way down” is probably familiar with the image of the world being carried on the back of a giant turtle. While that philosophical one-liner is of relatively modern vintage, the cosmic turtle mytheme has appeared in disparate cultures across the globe for millennia. In honor of everyone’s favorite intellectual quandary, let’s take a moment to celebrate the tortoises that hold up the world.

In his book Researches Into the Early History of Mankind and the Development of Civilization, the turn-of-the-20th-century anthropologist Edward Burnett Tylor writes that the world turtle concept likely first appeared in Hindu mythology. In one Vedic story, the form of the god Vishnu’s second avatar, Kurma, is a great turtle, which provides a celestial foundation upon which a mountain is balanced.

Over in China, part of the traditional creation mythology involves a giant turtle named Ao, although the image in this case is a bit different. According to the legend, the creator goddess cut off the legs of the cosmic turtle and used them to prop up the heavens, which had been damaged by another god. It’s not quite carrying the world on its back, but it still puts a terrapin at the center of the universe, making sure that the very sky doesn’t fall down.

The concept of a world turtle seems to have arisen independently within Native American myth and legend. In the creation stories of the Lenape and Iroquois people, the Earth is created as soil is piled on the back of a great sea turtle that continues to grow until it is carrying the entire world. Many indigenous tribes in North America refer to the continent as Turtle Island to this day.

The image of the world being carried through space by an ancient, impossibly massive tortoise is evocative, so it’s not hard to imagine why it has survived for so long in so many different cultures. But in the end, why turtles?

In a 1974 issue of the anthropological journal Man, the scholar Jay Miller provides some thoughts on what makes the turtle such a popular world bearer, writing, “I viewed the turtle as a logical choice for such an atlantean because its shape and appearance were suited to this role.” But he goes on to write, specifically of the Lenape belief in a world turtle, that the creature also mirrored aspects that they valued in their culture, such as perseverance and longevity. And that idea doesn’t just apply to the cosmic turtle in Lenape culture. “With intensive research, the above analysis should also apply for other societies that place the earth on the back of a turtle.” Most turtles and tortoises are also famously long-lived, giving them a wise, ancient quality that lends itself to mythologizing.

World turtles appear in more modern pop culture as well, from the Great A’Tuin of the late Terry Pratchett’s Discworld franchise, to the all-knowing Maturin of Stephen King’s metaverse. Clearly, it remains cool to imagine that our world is being led through space by a being that actually knows where we’re headed.

Why Is the World Always on the Back of a Turtle?” As Eric Grundhauser (@OMGrundhauser) explains, it’s mythology all the way down.

* Stephen King


As we contemplate cosmological chordates, we might recall that it was on this date in 762 that Baghdad was founded. After the fall of the Umayyads, the first Muslim dynasty, the victorious Abbasid rulers wanted their own capital from which to rule. They chose a site north of the Sassanid capital of Ctesiphon— a site especially blessed as it had control over strategic and trading routes along the Tigris, and it had an abundance of water in a dry climate. The caliph Al-Mansur commissioned the construction of the city– in the round, a deliberate reminder of an expression in the Qur’an, when it refers to Paradise.

Within a short time, Baghdad evolved into a significant cultural, commercial, and intellectual center of the Muslim world. This, in addition to housing several key academic institutions, including the House of Wisdom (see also here), as well as hosting a multi-ethnic and multi-religious environment, earned the city a worldwide reputation as the “Center of Learning.”

Baghdad was the largest city in the world for much of the Abbasid era during the Islamic Golden Age, peaking at a population of more than a million. But the city was largely destroyed at the hands of the Mongol Empire in 1258, resulting in a decline– fueled by frequent plagues and the turmoil of multiple successive empires– that lingered through many centuries.


Written by (Roughly) Daily

July 30, 2021 at 1:00 am

“Those who wish to know the art of calculating, its subtleties and ingenuities, must know computing with hand figures”*…

Scholars at an Abbasid library. Maqamat of al-Hariri Illustration by Yahyá al-Wasiti, 1237 [source]

The House of Wisdom sounds a bit like make believe: no trace remains of this ancient library, destroyed in the 13th Century, so we cannot be sure exactly where it was located or what it looked like.

But this prestigious academy was in fact a major intellectual powerhouse in Baghdad during the Islamic Golden Age, and the birthplace of mathematical concepts as transformative as the common zero and our modern-day “Arabic” numerals.

Founded as a private collection for caliph Harun Al-Rashid in the late 8th Century then converted to a public academy some 30 years later, the House of Wisdom appears to have pulled scientists from all over the world towards Baghdad, drawn as they were by the city’s vibrant intellectual curiosity and freedom of expression (Muslim, Jewish and Christian scholars were all allowed to study there).

An archive as formidable in size as the present-day British Library in London or the Bibliothèque Nationale of Paris, the House of Wisdom eventually became an unrivalled centre for the study of humanities and sciences, including mathematics, astronomy, medicine, chemistry, geography, philosophy, literature and the arts – as well as some more dubious subjects such as alchemy and astrology.

To conjure this great monument thus requires a leap of imagination (think the Citadel in Westeros, or the library at Hogwarts), but one thing is certain: the academy ushered in a cultural Renaissance that would entirely alter the course of mathematics.

The House of Wisdom was destroyed in the Mongol Siege of Baghdad in 1258 (according to legend, so many manuscripts were tossed into the River Tigris that its waters turned black from ink), but the discoveries made there introduced a powerful, abstract mathematical language that would later be adopted by the Islamic empire, Europe, and ultimately, the entire world.

Tracing the House of Wisdom’s mathematical legacy involves a bit of time travel back to the future, as it were. For hundreds of years until the ebb of the Italian Renaissance, one name was synonymous with mathematics in Europe: Leonardo da Pisa, known posthumously as Fibonacci. Born in Pisa in 1170, the Italian mathematician received his primary instruction in Bugia, a trading enclave located on the Barbary coast of Africa (coastal North Africa). In his early 20s, Fibonacci traveled to the Middle East, captivated by ideas that had come west from India through Persia. When he returned to Italy, Fibonacci published Liber Abbaci, one of the first Western works to describe the Hindu-Arabic numeric system.

When Liber Abbaci first appeared in 1202, Hindu-Arabic numerals were known to only a few intellectuals; European tradesmen and scholars were still clinging to Roman numerals, which made multiplication and division extremely cumbersome (try multiplying MXCI by LVII!). Fibonacci’s book demonstrated numerals’ use in arithmetic operations – techniques which could be applied to practical problems like profit margin, money changing, weight conversion, barter and interest…

Fibonacci’s great genius was not just his creativity as a mathematician, however, but his keen understanding of the advantages known to Muslim scientists for centuries: their calculating formulas, their decimal place system, their algebra. In fact, Liber Abbaci relied almost exclusively on the algorithms of 9th-Century mathematician Al-Khwarizmi. His revolutionary treatise presented, for the first time, a systematic way of solving quadratic equations. Because of his discoveries in the field, Al-Khwarizmi is often referred to as the father of algebra – a word we owe to him, from the Arabic al-jabr, “the restoring of broken parts”—and in 821 he was appointed astronomer and head librarian of the House of Wisdom…

Centuries ago, a prestigious Islamic library (tragically burned in the the Siege of Baghdad) brought Arabic numerals to the world; its mathematical revolution changed our world: “How modern mathematics emerged from a lost Islamic library.”

For more on The House of Wisdom– and the sad stories of other libraries and archives that have been destroyed through the ages– see Richard Ovenden‘s remarkable new Burning the Books- a History of the Deliberate Destruction of Knowledge.

* Leonardo da Pisa, known posthumously as Fibonacci [see here]


As we count our blessings, we might spare a thought for John Pell; he died on this date in 1685.  An English mathematician, he is perhaps best remembered for having introduced the “division sign”– the “obelus,” a short line with dots above and below– into use in English.  It was first used in German by Johann Rahn in 1659 in Teutsche Algebra; Pell’s translation brought the symbol to English-speaking mathematicians.  But Pell was an important influence on Rahn, and edited his book– so may well have been, many scholars believe, the originator of the symbol for this use.  (In any case the symbol wasn’t new to them:  the obelus [derived from the word for “roasting spit” in Greek] had already been used to mark passages in writings that were considered dubious, corrupt or spurious…. a use that surely seems only too appropriate to legions of second and third grade math students.)


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