Chapter 8 – Paolo Toscanelli’s Florence

Chapter summary:
Between the acquisition of the port of Pisa in 1406 and that of Livorno in 1421, Florence had enjoyed a continuous economic boom. Florence’s access to Venice enabled her to reap some of the benefits of Venice’s trade with the East. It also exposed the city to an influx of Chinese and other Asians, as we can see from period paintings and sculpture. Ambrogio Lorenzetti, who never left Tuscany, painted The Martyrdom of Francescan Friars in the church of San Francesco Siena, depicting Chinese merchants with conical hats. Previously, oriental eyes had appeared in faces painted by Giotto and Duccio. There was a very substantial Chinese and Mongolian population in Florence in the decades after 1434.

For the next hundred and fifty years, Medici power and money fired the Renaissance.
The Renaissance produced an enormous appetite for talent — engineers, astronomers, mathematicians and artists whose individual works were so widely acclaimed that others were inspired to follow with confidence. The Chinese delegation, with their new ideas, fabulous inventions and depth of culture would have made a very forceful impression on Florentine intellectuals, including Paolo del Pozzo Toscanelli. Florence was the ideal loam for Chinese intellectual seeds.

Cosimo de Medici took a dramatic turn after 1434, embarking on an orgy of patronage. He financed exotic palaces and chapels – San Lorenzo, San Marco and the Medici Palace. Cosimo and his brother Lorenzo’s embellishment of the sacristy at San Lorenzo was a notable insertion of science into the very heart of the church: in the little dome above the altar, an astronomical fresco depicted the position of the sun, moon and stars for 6 July 1439, the official day of union between the Eastern and Western Churches signed at the Council of Florence. This scientifically accurate depiction of a particular day’s sky was unfamiliar. The position of the sun, moon and stars for 6 July 1439 were all remarkably accurate. The puzzling question is how did Cosimo’s artist — without the benefit of computer based astronomical tables — know the position of the sun, moon and stars for 6 July 1439?

Someone knew the precise positions of the stars relative to each other, as well as the positions of the sun and moon relative to each other and to the stars. Whoever painted that fresco understood the solar system. This complex painting required years to execute, during which the position of the stars relative to the earth would have changed according to the 1,461-day cycle. It could not have resulted from piecemeal observations over the course of the job – my conclusion is that the artist had access to accurate astronomical tables.

Author James Beck, in Leon Battista Alberti and the Night Sky at San Lorenzo, has shown that the painter was Leon Battista Alberti, perhaps assisted by his friend Paolo Toscanelli. These two were Florence’s leading astronomers and mathematicians in 1439. Alberti in 1434 had accompanied Eugenius IV to Florence, where he met Toscanelli. The most likely explanation of the fresco mystery is that Alberti, who served as the Pope’s notary, met the Chinese delegates and obtained a copy of the astronomical calendar presented by the Chinese to Eugenius IV. The calendar provided the necessary information of right ascensions and declinations of stars to draw the night sky for a particular day and hour.

Further reading:
Zheng He’s delegation to the Papal Court of Florence by Tai Peng Wang – click here

Slaves in Florence, by Lynn White
http://www.jstor.org/pss/1849619

The Domestic Enemy: The Eastern Slaves in Tuscany in the Fourteenth and Fifteenth Centuries by Iris Origo: http://www.jstor.org/pss/2848074

Asiatic Exoticism in Italian Art of the Early Renaissance, by Leonardo Olschki
http://www.jstor.org/pss/3046937

Paolo dal Pozzo Toscanelli:
http://www.newadvent.org/cathen/14786a.htm

Tradition and Innovation in Fifteenth Century Italy: “Il Primato Dell’ Italia” in the Field of Science, by Dana B. Durand: http://www.jstor.org/pss/2707234

Florentine Interest in Ptolemaic Cartography as Background for Renaissance Painting, Architecture, and the Discovery of America, by Samuel Y. Edgerton, Jr.: http://www.jstor.org/pss/988935

Laetentur Caeli: The Council of Florence and the Astronomical Fresco in the Old Sacristy by Patricia Fortini Brown: http://www.jstor.org/pss/751062

Leon Battista Alberti and the “Night Sky” at San Lorenzo by James Beck
http://www.jstor.org/pss/1483282

Salvatore Bongi “Le Sciave Orientali in Italia” In Nuova Antologia II (1866)
Vincenzo Lazzari “Del Traffico e delle Condizioni Degli Schiavi in Venezia” (Turin 1862)
Agostini Zanella “Le Schiave Orientali A Firenze Nei Secoli, XIV e XV” (Florence 1885).

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