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Scholar discovers handwritten notes by Galileo in old math text book [1]

['Séamus Bellamy']

Date: 2026-03-03  

Trawling through academic archives can be an absolute drag: I've spent weeks up to my neck in old books, microfiche, loose paperwork, and scanned documents looking for a useful tidbit but coming up with bupkis. But every now and then, the digging through history pays off in absolute gold, as University of Milan scholar Ivan Malara recently discovered.



Malara was hip deep in research, cruising through a copy of Ptolemy's Almagest as one does. The Reader's Digest version (old folk-speak for TLDR) of the text is that it enshrined the notion that the earth lay at the center of the universe and that everything else revolves around it. Malara's area of study has led him to encounter the work of famed mathematician and astronomer Galileo Galilei: You may know him as the fella who supported the work of astronomer Nicolaus Copernicus, arguing that the Earth revolved around the Sun and that Ptolemy was full of shit. It made him really popular with the church crowd.

Anyway, back to Malara. As he looked through the 15th-century edition of Ptolemy's second-century Almagest, he saw that someone had been scribbling notes in the margins. After years of focused research, he could have recognized that chicken scratch in his sleep: it belonged to Galileo.



The hypothesis that guided my research may seem bold, even paradoxical: perhaps one of the decisive factors that led Galileo to embrace Copernicus' doctrine was precisely his mastery of the more specialised aspects of Ptolemy's Almagest. Admittedly, these were two opposing cosmological systems: Copernicus' heliocentric and Ptolemy's geocentric. However, it is also true that they were both formulated in the same mathematical language and made use of largely shared astronomical techniques. Consequently, the Almagest provided Galileo with the grammar he needed to understand De revolutionibus.



That Galileo had studied Ptolemy's work isn't surprising. Proving it to be the case, however, was. Malara's account of the steps he took to move his suspicions from fancy to fact makes for a fascinating read. What's more, he's promised to flesh out the details of his investigation at a later date. You can read his account of finding Galileo's notes and how it all went down here.

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[1] Url: https://boingboing.net/2026/03/03/scholar-discovers-handwritten-notes-by-galileo-in-old-math-text-book.html

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