Arno Pisa
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Leonardo gave us... the numbers

This isn't about the genius of da Vinci but rather about another Leonardo: Leonardo Fibonacci, better known as Leonardo da Pisa.

From "Slowtuscany": Stories about Tuscany by Damiano Andrei

Translation by: Andrea Brown, Giovanna Novelli, Munmun Gosh

I would propose you a short arithmetical question: MCLII – XXX = MCXXII.  Is this not clear? OK, then let’s try and write it again with the figures we conventionally use: 1152 – 30; Yes!  This is absolutely clear now, as well as the result: 1122.  Only because these figures are well known to us, but let’s find out when did we get used to them?  It’s easy… It goes back to the time in which Leonardo introduced them to the western world, through the Arab people. I can imagine the astonished reaction from  many of you: “ Again, we owe this novelty to the genius from Vinci?”… but I’m sorry, I must immediately stop, this time, your enthusiasm: the fact is that we are surely talking about Leonardo and particularly, that Leonardo Fibonacci better known as Leonardo from Pisa, who was born in the town of the leaning tower three centuries earlier than the famous homonym from Vinci.

We have little biographical details about Leonardo Fibonacci, the only things we know of his life come out from his mathematical  and geometric treatises. He was born in Pisa around 1170 but left his country very soon, to reach his father in the commercial colony of Pisa called Bùgia, a rich and prosperous Islamic town in  northern Tunisia.When in Muslim land, where he surely lived between 1180 and 1185, he furtherly approached the mathematics  and arithmetic, whose knowledge was largely owned by the Arab people.  During this period, he got to know the nine figures we still know today in the similar way (1,2,3,4, etc.). Fibonacci then traveled throughout many countries, probably thanks to his trading and he often remembers Greece, Sicily and Provence in his memories. It was during those journeys that he further grew his knowledge about mathematics, till to know everything taught in the schools of those countries (at the Constantinople Court  his knowledge  even got him the wonder  by  the great Greek mathematicians). 

When he returned to Italy, in the early years of ‘200, he concentrated all his knowledge in the “Liber Abaci” (the Book of Numbers), milestone of the medieval scientific knowledge. It is thanks to this book that the Indo-Arabic numeral system was introduced to the Latin-western world. It was an extraordinary revolution, if we think that before the drawing of this book (we are in 1202) Europe only knew the Roman numeral for its trading, mathematical, statistic and other kind of calculations. The simplifications for many scholars, merchants, architects and duty officers etc., were enormous. The text immediately spread everywhere and recognition was not late: even  the powerful Emperor Friedrich II, one of the greatest intellectual geniuses of that time, while going from Sicily to Lombardy, purposely stopped in Pisa to meet him.

After this meeting and further to writing other arithmetic and geometric treatises, the traces of the greatest mathematician  of medieval Latin time are almost totally lost. Nobody knows the date of his death; according to a historian from Pisa, he was killed during one of the recurring fights amongst factions; according to others, he spent his latest days in peace. Any way, despite the  memory of this illustrious man from Pisa has been partially overshadowed, we can undoubtedly say, today, that Leonardo Fibonacci ‘gave the numbers’* … to the world!

*(a short explanation: literally, in Italian, ‘to give the numbers’ means: ‘to be off one’s mind’!) -







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