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Primary sourceBook1638

Two New Sciences

Galileo Galilei · 1638

Galileo's final book, written under house arrest, founding the modern study of motion and the strength of materials.

Galileo's final scientific testament, written and smuggled abroad for publication while he was under house arrest.

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Title page of Galileo Galilei's 'Discorsi e Dimostrazioni Matematiche, intorno a due nuove scienze' (1638), printed in Leiden by the Elzevirs. Engraved vignette of a man beneath a tree with a banner reading 'Non solus'.
Galileo Galilei, Discorsi e Dimostrazioni Matematiche intorno a due nuove scienze, title page, Leiden, 1638.

About this source

What it is

Discourses and Mathematical Demonstrations Relating to Two New Sciences is Galileo Galilei's last book, published in 1638 in Leiden, Holland, since the Inquisition had banned publication of his work in Catholic lands. Written partly in Italian and partly in Latin, it again uses the dialogue form with the characters Salviati, Sagredo and Simplicio.

Why it matters

The book summarises thirty years of Galileo's work on physics, covering why materials break, how objects fall, and how projectiles move. It is considered a foundation of the modern science of motion and engineering, written while Galileo was confined after his trial, showing his determination to keep working despite the Church's ban.

Look closer

  • Why might Galileo have had the book published abroad rather than in Italy?
  • What does the choice of a dialogue, with characters representing different stages of Galileo's own thinking, suggest about how he wanted readers to follow his reasoning?
  • What everyday examples does the text use to explain scientific ideas, and why might that make them easier to understand?

This book is part of the curated material that grounds the AI version of Galileo Galilei on Humy.ai — when students ask about related events, the AI can quote it and cite it.

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Title page of the 1610 Latin book Sidereus Nuncius by Galileo Galilei, printed in Venice by Thomas Baglionus. Black text in several type styles, with a central woodcut emblem of a seated figure in an oval frame flanked by cherubs. Handwritten shelfmark appears at the bottom.Book

Primary source

Sidereus Nuncius

Galileo Galilei · 1610

Engraved oval portrait print of a bearded older man with receding hair, wearing a white collar and a buttoned dark coat, in an oval frame. Inscribed 'Galileus Galileus Florentinus' at top, 'Eques Octavius Leonus' and 'Romanus pictor fecit' at bottom, and dated '16 24' with 'Superiorum licentia'. Printed on cream paper with a grayscale color scale at right.Painting

Primary source

Portrait of Galileo Galilei (1624 print)

1624

Oil portrait of an elderly bearded man with a white collar, wearing a black robe, seated at a table with books, a pair of dividers in his raised hand, and a celestial globe to the left, in a dark background. A brass plaque on the frame reads Galileo Galilei.Painting

Primary source

Oil Portrait of Galileo in His Study

Unknown Italian painter · 18th century (?)

Oval-framed line engraving of an older bearded man in a large white collar and dark doublet, with a Latin inscription above reading Galileus Galileus Florentinus, and an artist credit below. Handwritten Italian caption on mount beneath.Painting

Primary source

Galileo Galilei, line engraving by Ottavio Leoni

Ottavio Leoni · 1624

Title page of the 1632 Florentine edition of Galileo Galilei's Dialogo, printed in large serif capitals with a decorative woodcut emblem, imprint 'In Fiorenza, Per Gio: Batista Landini MDCXXXII', and several library stamps and handwritten shelf marks.Book

Primary source

Dialogue Concerning the Two Chief World Systems

Galileo Galilei · 1632

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