For over eight hundred years the façade of the church of San Nicola in Pisa has watched over a message that nobody has ever read before. Recently the front has been restored and the marble cleaned. During the process a professor of the University of Pisa, Pietro Armienti, an expert in petrology, closely observed the circular and rectangular inlays of one of the church’s lunettes and discovered a coded message. Studying its geometry the professor realized that the symbols were an explicit reference to the findings of the first great western mathematician Leonardo Fibonacci, who was born in Pisa around 1170. Professor Armienti has just published his research report on “Journal of Cultural Heritage”.
The Church of San Nicola has a first mention in 1097. In 1297-1313 the Augustinians enlarged it probably under design by Giovanni Pisano. During the following centuries the ravages of time left its mark on the inlays of the façade making them unreadable. After its recent restoration, the message carved in the lunette of the portal has emerged with all its details, proving to be a valuable artefact which celebrates the insights that marked the birth in Pisa of a school of thought that transformed the medieval vision of the world and turned Pisa into the cradle of modern scientific thought.
Apparently studying the diameters of the various circles one obtains the first nine elements of the Fibonacci sequence: 1,2, 3, 5, 8, 13, 21, 34 and 55. According to Professor Armienti the reference could not be more explicit and directly connects the inlay to the work of the great mathematician, or at least to a circle of his immediate colleagues or students. It appears that the inlay is an abacus which represents irrational numbers as well as made to calculate with good approximation the sides of the regular polygons inscribed in the circle with the largest diameter.
This is thus an important monument designed to instruct the elites according to the Scholastic programme. A precious gift which has been sent down to us from over eight hundred years ago and which can finally be valued.