The work is considered by many to be the smallest book in the world printed with movable type. The character used is "fly's eye" engraved in 1834 by Antonio Farina from Piacenza and used by the same publisher for the famous lowercase edition of Dante from 1878. The Letter to Cristina is one of the central texts of Galileo's reflection on the relationship between science and faith; it compares the book of nature and the sacred book on the relationship between mobility and immobility, centrality and non-centrality of earth and sun, showing the singularity of the two books and demonstrating that it is not relevant to read the characters of nature through the text of the Bible. The letter was written by Galileo in 1615; it was printed only twenty years later, in 1636, by the Elzeviers in Strasbourg, and was accompanied in parallel by the Latin translation by Elia Diodati.

Spielmann, Catalogue of the library of miniature books,< /i> 161: "One of the most famous and popular miniature book in existence"; Welsh, A bibliography of miniature books, 2935.