A remarkable discovery for the history of science has been made at the Biblioteca Nazionale Centrale di Firenze (BNCF): a printed copy of Ptolemy’s Almagest, published in Basel in 1551, bearing numerous marginal annotations attributable to Galileo Galilei. The discovery is the work of Ivan Malara, a young researcher affiliated with the Università Statale di Milano, following more than three years of investigation into Galileo’s direct engagement with this foundational astronomical treatise.

The annotated volume was identified in the Fondo Magliabechiano of the BNCF during a systematic examination of early printed editions of the Almagest held in Florentine libraries. Palaeographic and textual analysis of the marginal notes reveals a strong correspondence with Galileo’s early handwriting and with specific passages from his works written both before and after the Sidereus Nuncius (1610). The find suggests that Galileo’s deep mastery of the Ptolemaic system may have been a key factor in his eventual embrace of Copernican heliocentrism.

The discovery was presented at a press conference at the BNCF on 17 February 2026. It opens new avenues of research within the library’s collections, extending beyond the already-held Fondo Galileiano of 347 manuscripts into holdings not previously associated with Galileo’s personal library.

More information: https://bncf.cultura.gov.it/un-nuovo-postillato-di-galileo-galilei/