Galileo Galilei's 1638 Publication Process
Galileo Galilei continued his research under house arrest after his 1633 trial. Published in Leiden in 1638 through overseas contacts and a publisher's mediation, Two New Sciences presented his research on motion and the strength of materials.
Galileo was convicted on June 22, 1633, and recanted his position on heliocentrism.
Even after returning to Arcetri, he was prohibited from meeting visitors for scientific discussions.
Two New Sciences was published in Leiden in 1638 through the mediation of overseas contacts.
The book's two main subjects are the motion of bodies and the resistance of materials to failure.
Codex 72 contains research drafts from different periods, so its page order cannot be taken as the order in which they were written.
Galileo Galilei was placed under house arrest after his trial in 1633. With help from contacts abroad, he published Two New Sciences in 1638. This is remembered as a case in which research on mechanics was preserved in a book despite restrictions on the author's freedom.
This article follows the records of Museo Galileo and the manuscripts, as checked in November 2026.
What was restricted at the 1633 trial?
Galileo was convicted by the Inquisition because of his position on heliocentrism. The background included a 1616 order not to defend heliocentrism. His Dialogue Concerning the Two Chief World Systems, published in 1632, brought the issue before the Inquisition again.
The sentence was handed down in Rome on June 22, 1633. It found Galileo vehemently suspected of heresy. It also explicitly banned Dialogue Concerning the Two Chief World Systems. These details can be found in the sentence on the Museo Galileo website.
I, Galileo Galilei, have abjured as stated above and sign with my own hand.
This is Galileo Galilei's handwritten confirmation in Galileo's Abjuration, dated June 22, 1633.
The wording of the punishment in the sentence must be distinguished from his subsequent living conditions. The sentence specified imprisonment by the Inquisition. In practice, his subsequent supervision took the form of house arrest, restricting where he could live. The fact that he stayed at home does not mean he was allowed to conduct research freely.
Timeline from the trial to publication
Between the trial and publication came restrictions on his residence and efforts to pass the manuscript through intermediaries. After the trial, Galileo stayed at the archbishop's residence in Siena. Restrictions continued after he returned to Arcetri at the end of the same year.
Date or period | Event | Supporting source
February 26, 1616 | Warned not to hold, teach, or defend heliocentrism | Museo Galileo's chronology of Galileo's life
1632 | Dialogue Concerning the Two Chief World Systems published | Museo Galileo's chronology of Galileo's life
June 22, 1633 | Conviction and abjuration of his position | The sentence and chronology of his life
After the 1633 trial | Stayed at Archbishop Ascanio Piccolomini's residence in Siena | Museo Galileo's account of his work
December 1, 1633 | Granted permission to return to Arcetri, with contact with visitors for scientific discussion prohibited | Museo Galileo's chronology of Galileo's life
February and March 1635 | Micanzio informed Galileo by letter of a blanket ban on publishing his works | A 2025 study of the publication history
1636 | Elzevir agreed to publish Two New Sciences | Museo Galileo's account of his work
July 1638 | Printing of Two New Sciences completed in Leiden | Museo Galileo's chronology of Galileo's life
January 8, 1642 | Died in Arcetri | Museo Galileo's account of his residence
The date permission to return was granted is not the same as the date of actual arrival. December 1 in the museum's chronology is the date permission was granted. When citing the chronology, the nature of the event must also be stated. The correspondence between dates and events follows the museum's chronology of Galileo's life.
How did research continue under house arrest?
Galileo reorganized his long-standing research on motion and matter. The contents of Two New Sciences were not developed entirely after the trial. He continued reviewing earlier research and refining his arguments.
His residence in Arcetri was a villa called Il Gioiello. The conditions of his return included a ban on contact with visitors who would discuss scientific matters. This restriction is stated in Museo Galileo's account of the villa.
Even so, scholarly exchange continued through letters and manuscripts. Contacts abroad read the manuscript and sent comments. The arrangements needed for publication also proceeded through this network. The continuation of research should not be interpreted to mean that all exchanges were permitted.
Declining health also made writing more difficult. The museum's chronology records his blindness in 1638. However, the date of his blindness cannot be taken as the date when the entire book was written. The book includes research written earlier.
The overseas contacts that made publication in Leiden possible
The turning point in publication came when the manuscript reached publishers abroad. The ban on granting printing permission for Galileo's works was also an obstacle to his new book on mechanics. Leiden was not a place where the Roman Inquisition's ban was enforced in the same way.
Museo Galileo describes Fulgenzio Micanzio's role as an intermediary. Micanzio helped get the manuscript to Elzevir in the Netherlands. Elia Diodati was another key figure in the network working toward publication. Several people were involved in passing on the manuscript and negotiating publication.
Person or party | Documented role in publication | Type of evidence
Galileo | Organized the research, wrote the manuscript, and took part in the publication process | Research analyzing manuscripts and letters
Fulgenzio Micanzio | Acted as an intermediary in passing on the manuscript and preparing it for printing | Museum accounts of individuals and works
Elia Diodati | Took part in overseas publication negotiations and plans to conceal the author's involvement | A 2025 study of handwriting and letters
The Elzevir publishers | Printed and published the book in Leiden | Bibliographic records of the first edition and the museum's chronology
The dedication describes events as though the news of publication had come as a surprise. However, it is difficult to treat this as evidence that the author was not involved in publication. A 2025 study presents evidence of Galileo's active involvement. This interpretation is based on a paper analyzing manuscripts and letters.
What did Two New Sciences explain?
The book's two central subjects are the strength of materials and the motion of bodies. The strength of materials is their ability to withstand forces without breaking. The research on motion covers topics such as falling bodies and the paths of thrown objects. The University of Oklahoma Libraries' description of its copy also presents this distinction.
Subject | Questions addressed in the book | Explanation to aid understanding
Strength of materials | The size and shape of bodies and their resistance to breaking | Whether a large structure can be built by scaling up a small one in the same proportions
Falling motion | The laws governing the motion of falling bodies | Explaining falling motion through mathematical relationships
Parabolic motion | The path traced by a thrown object | Explaining projectile motion mathematically
The discussion of materials also includes an explanation of the bones of large animals. To support a larger body, the thickness of the bones must also change. The point is that simply enlarging a body in the same proportions is not enough. This shows that the book's concerns were not limited to celestial matters.
The book takes the form of a dialogue among Salviati, Sagredo, and Simplicio. This dialogue is a literary form used to develop arguments. It is not a transcript of the actual trial. The characters' statements should not be quoted as though they were courtroom testimony.
Its title also needs to be distinguished from Dialogue Concerning the Two Chief World Systems. The two books differ in their publication dates and central subjects. Two New Sciences is not a judicial ruling that directly proved heliocentrism.
Work | Year of publication | Main subject
Dialogue Concerning the Two Chief World Systems | 1632 | Discussion of the Ptolemaic and Copernican systems of the universe
Two New Sciences | 1638 | Research on the strength of materials and motion
What manuscript arrangement and shelf marks tell us
The sequence of discoveries cannot be reconstructed from the page order of a manuscript alone. Codex 72 at the National Central Library of Florence is one example. It preserves drafts in the handwriting of Galileo and his pupils.
The Max Planck Institute for the History of Science describes a mixture of text, diagrams, and calculations. Much of the material is connected to the theorems on motion in Two New Sciences. The institute has linked the relevant theorems and drafts so that readers can find them. Its explanation appears in “Contents of the Manuscript”.
The drafts were written at different times. Their current arrangement does not follow the order in which they were written. A draft appearing later in the manuscript therefore cannot be assumed to represent a later discovery. Understanding the writing done after the trial requires examining the nature of each record.
A 2015 publication from the National Library of Spain also introduces this book. It lists the 1638 work under the shelf mark 3/r49976. This is a way to identify an item in the collection. It is not an indication of when Galileo wrote it.
Marker in the record | What it establishes | What that marker alone cannot establish
The date 1638 in the first edition | The year of publication | The year in which all the research was conducted
The page order of Codex 72 | The current arrangement of the material | The chronological order of discovery and writing
A library shelf mark | Identification of an item at that institution | When the manuscript was written or how publication was negotiated
These distinctions are useful when reading records from several countries together. Museum chronologies and manuscripts answer different questions. Library bibliographic records are used to confirm a book's edition and holdings information. The Spanish holdings information can be found in the search index of the National Library's publication.
How far do records and interpretations agree?
The sentence and publication are documented events, but interpreting the publication strategy involves judgment. The author's dedication must also be read with its purpose in mind. What historical sources say needs to be distinguished from the judgments of later researchers.
Facts established by the records
The sentence shows the basis for the abjuration and the ban on the book. The chronology of Galileo's life records permission to return and publication in 1638. Codex 72 preserves research drafts connected to the published book. These materials provide evidence from different stages.
Points commonly explained in the research
Museum accounts and studies of publication history recognize the role of overseas contacts. Two New Sciences is described as a work bringing together many years of research. Its publication is not seen as a victory in the trial held during his lifetime. The Vatican Observatory's biographical account also explicitly states that he remained under house arrest for the rest of his life.
Hypotheses and points requiring caution
The 2025 paper proposes that Diodati wrote the relevant manuscript. This is based on handwriting comparisons and a reconstruction of publication activities. It must be distinguished as a hypothesis put forward by that study. The dedication alone also cannot establish the actual extent of Galileo's involvement.
The outcome of publication and its meaning today
The publication of Two New Sciences provided a channel for communicating research on mechanics. It did not result in Galileo's release from house arrest. He spent the rest of his life with his freedom restricted. This is also confirmed in the Vatican Observatory's biographical account.
This case encourages us to examine the Scientific Revolution through both research findings and the processes by which they circulated. Writing required the work of organizing arguments. Publication required people to pass on the manuscript and take charge of printing. Readers today can compare the surviving drafts with the printed book.
Frequently asked questions
Was Galileo acquitted at his trial?
Galileo was convicted at his trial in 1633. He recanted his position on heliocentrism. The publication of his book in 1638 should not be described as an acquittal or the lifting of his punishment.
Was Two New Sciences written entirely from scratch under house arrest?
The book includes research that began before his house arrest. Galileo organized and developed it under restrictions. The manuscripts were not all written at the same time either.
Why was it published in Leiden rather than Italy?
Because there was a ban on publishing Galileo's works. Overseas contacts connected the manuscript with the Elzevir publishers. In Leiden, the Roman Inquisition's ban was not enforced in the same way.
Did Two New Sciences prove heliocentrism?
The book focuses on the strength of materials and the motion of bodies. It also discusses the laws of falling bodies and the parabolic motion of projectiles. It is inaccurate to present it as a book that directly proved heliocentrism or overturned the trial's outcome.
Was Galileo completely unaware of the publication?
The dedication describes the news of publication as though it had come as a surprise. However, research on letters and manuscripts shows his involvement in publication. It is difficult to accept the dedication's account as a factual description of the entire publication process.
Is Codex 72 the complete manuscript of Two New Sciences?
Codex 72 is a collection of drafts from different periods. It contains text, diagrams, and calculations. Some theorems are connected to the published book, but it is not the same as a complete manuscript of the entire book.
What does the National Library of Spain's material confirm?
The 2015 publication lists the 1638 work and its shelf mark. This provides a basis for identifying the library item. This information alone cannot establish the route by which the manuscript was passed on or the author's involvement in publication.
