"Leonardo, no, not that Leonardo!"

Happy New Year - somewhat late but still heart-felt.

The only painting in the United States by the Leonardo you are thinking of is the portrait of Ginervra de'Benci, painted about 1474 (ok, late Middle Ages), currently on view at the National Gallery of Art, Washington, D.C. It is in a glass case and the back of the portrait is also on view. Quite something.

But, the Leonardo I really love, admire and thank, especially when I think of having to do trig again towards the end of this book, is Leonardo of Pisa. Sometimes called the "greatest mathematician of the Middle Ages", Leonardo loved the abstract beauty of mathematics. His portrait, not those of sitting Presidents, should be in every classroom and pupils should salute, bow or lay a wreath. We have more to thank him for than any politician.

Called Fibonacci by those of us who are grateful, he was the son of a businessman who represented the city-state of Pisa or directed a trading post for Pisa in North Africa in what is now Algeria.

Leonardo, born about 1170 A.D., while still young, travelled to North Africa with his father and there he learned about the Hindu-Arabic number system.

Until that time, Roman (yes, really) numerals were still in use in Europe. Imagine your math class:

XLIV divided by VII equals VII. Actually an easy problem. What about:

MCMLXVI divided by VII equals CCLXXXI. Well, thanks to Leonardo, the problem was simplified to

1967 divided by 7 = 281.

Leonardo watched merchants calculate, learned the new system and through his book, LIBER ABACI, the Book of Calculation, spread the use of Hindu-Arabic numerals throughout Europe.

He also contributed to intelligence tests, job assessment tests and general "damn I can't figure that out" tests with the development of the Fibonacci sequence:

0,1,1,2,3,5,8,13,_____ the next number is 21. 1 and 1 are 2, 2 and 1 are 3, 3 and 2 are 5, 5 and 3 are 8. It's supposed to have something to do with calculating how many rabbits you would have at the end of the year if you started with 2. The answer is "too many" but the calculation is fun.

This chapter of the book is full of rather silly questions - Where did the Northmen come from ? Answer: not the South.

On what was the feudal system based - feudalism.

OK, not funny but also not very challenging. Therefore, I will continue to read Michael Jecks excellent mysteries as well as those by Susanna Gregory, listen to the BBC radio's excellent series about THE SECRET SCIENTISTS and tell you with the next post why we should also know about them.