Trail3 steps

Golden threads

Numerals, rabbits, Leonardo and the balance sheet.

Three ideas from Renaissance Italy, linked by mathematics, money and one remarkable friendship.

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I
A merchant’s son brings new numerals to Europe.
No. 040PersonMathematics
Fibonacci’s real legacy wasn’t the sequence The rabbit puzzle made him famous, but Fibonacci’s real impact was teaching Europe to write numbers the way we do now.
II
Those numerals make merchant accounting practical, and a friar writes the first printed guide.
No. 035ConceptEconomics
Leonardo’s math teacher wrote the first guide to accounting The friar who taught Leonardo da Vinci mathematics also published the first printed guide to double-entry bookkeeping, the system nearly every company still uses.
III
The same friar, with Leonardo, celebrates the “divine proportion”, which is surrounded by myths.
No. 047ConceptMathematics
The golden ratio is less magic than you’ve heard φ ≈ 1.618 really does appear in sunflowers and pentagons. Most claims about the Parthenon, the Mona Lisa and “perfect beauty” are myths.