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+--- Thread: How medieval Europe finally ditched Roman numerals + Why Plato traveled to Sicily (/thread-9671.html)
How medieval Europe finally ditched Roman numerals + Why Plato traveled to Sicily - C C - Jan 17, 2021
How Medieval Europe Finally Ditched Roman Numerals
https://www.discovermagazine.com/planet-earth/how-medieval-europe-finally-ditched-roman-numerals
EXCERPTS: There’s a joke that goes like this: Roman numerals. What are they good IV?
It’s a nice little number pun, but honestly, Roman numerals aren’t good for much - just try doing your taxes with them. By the sixth century A.D. (and possibly even earlier) a much better system, now called the Hindu-Arabic number system, was developed in India. It uses only 10 numerals: one through nine, plus zero - and only those numerals. No special symbol needed for 50, 100, a thousand, or any other number - just combinations of those 10 numerals.
The Hindu-Arabic system is a place-value system, meaning the position of a numeral indicates its value. So in the number 459, the four represents 400; the five represents 50. Lining the numbers up in columns makes quick work of addition and subtraction. A little carrying and borrowing and you’re solid on multiplication and division as well.
This may seem blindingly obvious to us, since that’s the numeric system we use now, but it wasn’t so clear to medieval Europeans. Up until the 13th century, they had to make do with Roman numerals. [...] Meanwhile, cultures that used the Hindu-Arabic system not only had an easier time with basic arithmetic, but they were also able to undertake more complex math. This enabled them to make big advances in algebra and geometry while Europeans toiled away with Roman numerals... (MORE - details)
Plato travelled to Sicily three times, risking his life to create a philosopher-king
https://aeon.co/essays/when-philosopher-met-king-on-platos-italian-voyages
EXCERPTS: . . . In Syracuse, Plato met a powerful and philosophically-minded young man named Dion, the brother-in-law of Syracuse’s decadent and paranoid tyrant, Dionysius I. Dion would become a lifelong friend and correspondent. This connection brought Plato to the inner court of Syracuse’s politics, and it was here that he decided to test his theory that if kings could be made into philosophers - or philosophers into kings - then justice and happiness could flourish at last.
Syracuse had a reputation for venality and debauchery, and Plato’s conviction soon collided with the realities of political life in Sicily. The court at Syracuse was rife with suspicion, violence and hedonism. [...] Plato’s efforts did not fare well. He angered Dionysius I with his philosophical critique of the lavish hedonism of Syracusan court life, arguing that, instead of orgies and wine, one needed justice and moderation to produce true happiness. However sumptuous the life of a tyrant might be, if it was dominated by insatiable grasping after sensual pleasures, he remained a slave to his passions.
Plato further taught the tyrant the converse: a man enslaved to another could preserve happiness if he possessed a just and well-ordered soul. Plato’s first visit to Sicily ended in dark irony: Dionysius I sold the philosopher into slavery. He figured that if Plato’s belief were true, then his enslavement would be a matter of indifference since, in the words of the Greek biographer Plutarch, ‘he would, of course, take no harm of it, being the same just man as before; he would enjoy that happiness, though he lost his liberty.’
Fortunately, Plato was soon ransomed by friends. He returned to Athens to found the Academy, where he likely produced many of his greatest works, including The Republic and The Symposium. But his involvement in Sicilian politics continued. He returned to Syracuse twice, attempting on both later trips to influence the mind and character of Dionysius II at the urging of Dion.
These three episodes are generally omitted from our understanding of Plato’s philosophy or dismissed as the picaresque inventions of late biographers. However, this is a mistake that overlooks the philosophical importance of Plato’s Italian voyages. In fact, his three trips to Sicily reveal that true philosophical knowledge entails action; they show the immense power of friendship in Plato’s life and philosophy; and they suggest that Plato’s philosopher-king thesis is not false so much as incomplete... (MORE - details)