No Zeros, No Way!
Florence bans the use of those newfangled Hindu-Arabic numerals. The abacists (meaning "those who write in the dust") are resisting the concept of a zero and decimal places introduced to Europe almost a century earlier by Leonardo Fibonacci of Pisa. Since God is everywhere, the idea of "nothing" is so foreign to them that it is seen as unnatural. Mathematics takes one in the shorts for now.  
John I of Holland is Down for the Count
Put on your detective hats. Here are the facts: in 1296 John I of Holland is 13 years old and the new Count of Holland. He is the son of Count Floris V of Holland, recently deceased in a plot to kidnap him, organized by King Edward I of England. Shortly thereafter King Edward has Young John come to England to educate him and to marry his daughter, Elizabeth, two years John's senior. Young John returns to Holland in 1297, without his new wife and tries to rule Holland through a regent who is neutral toward England. His regent is killed by a mob. Young John's wife finally shows up, arriving with King Edward, himself. John's new regent is a cousin, John II of Avesnes. Young John I drops dead shortly thereafter... of bad water ... at age 15. John II of Avesnes becomes the new Count. Does anyone suspect anything?  
Marco Polo Pops Out a Popular Travelogue from Prison
Marco Polo is captured at sea in battle while captaining a Venetian galley ship against Genoa. He is thrown in prison and dictates his famous "Travels of Marco Polo" from his prison cell to a fellow prisoner, Rustichello of Pisa who is actually a romance novelist. In this same year peace breaks out between Genoa and Venice and Marco Polo is released. His book, "The Travels of Marco Polo" or "The Description of the World" is received with skepticism by scholars but it will become popular and make him famous. It will also make the Silk Road popular, the road that the Black Plague will travel along to decimate Europe in the mid-1300s but for now all is well.    
- "The Encyclopedia of the Middle Ages: Leonardo Fibonacci", Norman F. Cantor, general editor, Viking Penguin, 1999, p.167
- Abacus, Wikipedia
- Fibonacci_numbers. N.N. Vorob'ev (originator), Encyclopedia of Mathematics.
- Scientists find clues to the formation of Fibonacci spirals in nature by Lisa Zyga, May 1, 2007
- Fibonacci retracement, Wikipedia
- Fibonacci Retracements, StockCharts, Chart Analysis (using examples of PetsMart and Target stock fluctuations)
- The Da Vinci Code (Film), in the film the curator writes a Fibonacci sequence in his own blood as a clue
- The history of Holland and the story of its ancient Capital and Residence Dordrecht, Part 2 by L. C. Geerts
- John I, Count of Holland, Wikipedia
- Marco Polo and His Travels, from the Silkroad Foundation, 2000.
- The Book of Ser Marco Polo, the Venetian by Marco Polo, translated and edited with notes, by Colonel Henry Yule, 1871
- The Description of the World, by Marco Polo, translated and annotated by A.C. Moule & Paul Pelliot, 1938
- The Travels of Marco Polo, Wikipedia