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Primary sourceLetter1615

Letter to the Grand Duchess Christina

Galileo Galilei · 1615

Galileo's 1615 essay arguing that scripture and the new astronomy need not contradict each other.

Galileo's own argument for reconciling his astronomy with scripture, written as the controversy over his ideas grew.

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Title page of a printed book reading 'Lettera del Signor Galileo Galilei Accademico Linceo scritta alla Granduchessa di Toscana', with a decorative floral woodcut ornament and the imprint 'In Fiorenza, MDCXX' at the bottom.
Galileo Galilei, Letter to the Grand Duchess Christina, printed edition, Florence, 1620.

About this source

What it is

This is a letter-essay written by Galileo Galilei in 1615, addressed to Christina of Lorraine, Grand Duchess of Tuscany. It expands an earlier letter to his student Benedetto Castelli about a dispute over whether the Earth's motion contradicted the Bible.

Why it matters

Galileo argued that the Bible teaches people how to reach heaven, not how the heavens physically work, and that scripture uses everyday language rather than literal scientific description. The letter became a key document in the long debate between science and religion, written as controversy over Copernican astronomy grew more dangerous for Galileo.

Look closer

  • Why would Galileo address a powerful noblewoman rather than publish his argument immediately?
  • What does his use of quotations from Church figures like St Augustine suggest about how he tried to defend himself?
  • Why wasn't the letter printed until after Galileo's later condemnation by the Inquisition?

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

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Galileo Galilei · 1610

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Portrait of Galileo Galilei (1624 print)

1624

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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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