''The Assayer'' ( it, Il Saggiatore) was a book published in

Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus (legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...

Galileo Galilei Galileo di Vincenzo Bonaiuti de' Galilei (15 February 1564 – 8 January 1642) was an Italian astronomer, physicist and engineer, sometimes described as a polymath. Commonly referred to as Galileo, his name was pronounced (, ). He wa ...

in October 1623 and is generally considered to be one of the pioneering works of the

scientific method The scientific method is an empirical method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...

, first broaching the idea that the

book of nature The Book of Nature within the relationship between religion and science, is a religious and philosophical concept originating in the Latin Middle Ages which views nature as a book to be read for knowledge and understanding. There also was a book ...

is to be read with mathematical tools rather than those of scholastic philosophy, as generally held at the time.

Grassi on the comets

The context of the essay was to reply to the treatise ''Libra astronomica ac philosophica'' of 1619 by

Orazio Grassi Orazio Grassi, S.J. (b. Savona 1 May 1583 – d. Rome 23 July 1654), was an Italian Jesuit priest, who is best noted as a mathematician, astronomer and architect. He was one of the authors in controversy with Galileo Galilei on the nature of ...

, a Jesuit mathematician at the

Collegio Romano The Roman College ( la, Collegium Romanum, it, Collegio Romano) was a school established by St. Ignatius of Loyola in 1551, just 11 years after he founded the Society of Jesus (Jesuits). It quickly grew to include classes from elementary school t ...

, which used the

pseudonym A pseudonym (; ) or alias () is a fictitious name that a person or group assumes for a particular purpose, which differs from their original or true name (orthonym). This also differs from a new name that entirely or legally replaces an individua ...

of Lotario Sarsi Sigensano. The debate between Galileo and Grassi started in 1618, when the latter published ''Disputatio astronomica de tribus cometis anni MDCXVIII'', in which he asserted that comets are celestial bodies. Grassi adopted

Tycho Brahe Tycho Brahe ( ; born Tyge Ottesen Brahe; generally called Tycho (14 December 154624 October 1601) was a Danish astronomer, known for his comprehensive astronomical observations, generally considered to be the most accurate of his time. He was ...

Tychonic system The Tychonic system (or Tychonian system) is a model of the Universe published by Tycho Brahe in the late 16th century, which combines what he saw as the mathematical benefits of the Copernican system with the philosophical and "physical" bene ...

, in which the other planets of the

Solar System The Solar System Capitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar ...

orbit around the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

, which, in turn, orbits around the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. In his ''Disputatio'' Grassi referenced many of Galileo's observations, such as the surface of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

and the phases of

Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never f ...

, without mentioning him. Grassi argued from the apparent absence of observable parallax that comets move beyond the Moon. Galileo never explicitly stated that comets are an illusion, but merely wondered if they are real or an optical illusion.

Science, mathematics, and philosophy

In 1616 Galileo may have been silenced on

Copernicanism Copernican heliocentrism is the astronomical model developed by Nicolaus Copernicus and published in 1543. This model positioned the Sun at the center of the Universe, motionless, with Earth and the other planets orbiting around it in circular p ...

. In 1623 his supporter and friend, Cardinal Maffeo Barberini, a former patron of the Accademia dei Lincei and uncle of future Cardinal Francesco Barberini, became Pope Urban VIII. The election of Barberini seemed to assure Galileo of support at the highest level in the Church. A visit to Rome confirmed this. ''The Assayer'' is a milestone in the history of science: here Galileo describes the

, which was quite a revolution at the time. The title page of ''The Assayer'' shows the crest of the

Barberini family The House of Barberini are a family of the Italian nobility that rose to prominence in 17th century Rome. Their influence peaked with the election of Cardinal Maffeo Barberini to the papal throne in 1623, as Pope Urban VIII. Their urban palace ...

, featuring three busy bees. In ''The Assayer'', Galileo weighs the astronomical views of a Jesuit, Orazio Grassi, and finds them wanting. The book was dedicated to the new pope. The title page also shows that Urban VIII employed a member of the Lynx, Cesarini, at a high level in the papal service. This book was edited and published by members of the Lynx. In ''The Assayer'' Galileo mainly criticized Grassi's method of inquiry, heavily biased by his religious belief and based on , rather than his hypothesis on comets. Furthermore, he insisted that

natural philosophy Natural philosophy or philosophy of nature (from Latin ''philosophia naturalis'') is the philosophical study of physics, that is, nature and the physical universe. It was dominant before the development of modern science. From the ancient wo ...

(i.e.

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

) should be mathematical. According to the title page, he was the philosopher (i.e. physicist) of the

Grand Duke of Tuscany The rulers of Tuscany varied over time, sometimes being margraves, the rulers of handfuls of border counties and sometimes the heads of the most important family of the region. Margraves of Tuscany, 812–1197 House of Boniface :These were origin ...

, not merely the mathematician. Natural philosophy (physics) spans the gamut from processes of generation and growth (represented by a plant) to the physical structure of the universe, represented by the cosmic cross-section. Mathematics, on the other hand, is symbolized by telescopes, and an astrolabe. This is the book containing Galileo’s famous statement that mathematics is the language of science. Only through mathematics can one achieve lasting truth in physics. Those who neglect mathematics wander endlessly in a dark labyrinth. From the book: Galileo used a sarcastic and witty tone throughout the essay. The book was read with delight at the dinner table by Urban VIII. In 1620 Maffeo Barberini wrote a poem entitled ''Adulatio Perniciosa'' in Galileo's honor. An official, Giovanni di Guevara, said that ''The Assayer'' was free from any unorthodoxy. Also in the book, Galileo theorizes that senses such as smell and taste are made possible by the release of tiny particles from their host substances, which was correct but not proven until later.

References

Sources

*Galileo Galilei, ''Il Saggiatore'' (in Italian) (Rome, 1623); ''The Assayer'', English trans.

Stillman Drake Stillman Drake (December 24, 1910 – October 6, 1993) was a Canadian historian of science best known for his work on Galileo Galilei (1569–1642). Drake published over 131 books, articles, and book chapters on Galileo. Including his translati ...

and C. D. O'Malley, in ''The Controversy on the Comets of 1618'' (University of Pennsylvania Press, 1960). *

Pietro Redondi Pietro Redondi (born 1950) is an Italian historian of science, known for his work on Galileo Galilei. Redondi obtained his doctorate in 1978 at the School for Advanced Studies in the Social Sciences in Paris, in the History of Science. In 1981- ...

, ''Galileo eretico'', 1983; ''Galileo: Heretic'' (transl: Raymond Rosenthal) Princeton University Press 1987 (reprint 1989 ); Penguin 1988 (reprint 1990 )

External links

PDF version of the abridged text of ''The Assayer'' - Stanford University

{{DEFAULTSORT:Assayer, The 1623 books Astronomy books History of astronomy Books by Galileo Galilei

Grassi on the comets

Science, mathematics, and philosophy

See also

References

Sources

External links