Life

 On February 15 Galileo Galilei, the son of Vincenzo Galilei (1520-1591), a Florentine musician, and Giulia Ammannati (1538-1620) from Pescia, is born in Pisa, in a house "located in the Chiasso dei Mercanti". On February 19 he is baptized in the Baptistery of the Pisa Cathedral.

 On September 5 Galileo is registered among the students of the Faculty of Arts at the University of Pisa.

According to Vincenzo Viviani (1622-1703), Galileo observes the isochronism of the oscillations of a pendulum in the lantern of the Pisa Cathedral. From this he will deduct that the period of pendulums of equal length is constant regardless of the amplitude of the oscillation. However, the first document in which the scientist formulates this principle is a letter to Guidobaldo del Monte (1545-1607) dated November 29, 1602. In reality, as was to be demonstrated in 1659 by the Dutch scientist Christiaan Huygens (1629-1695), isochronism is characteristic only of pendulums that perform cycloidal oscillations.

Unsatisfied by the conditions of his Pisan academic position, Galileo goes to Venice in August to request the chair of mathematics at the University of Padua, which the Venetian Senate assigns him on September 26. On December 7 he holds his inaugural lecture, and begins teaching on the 13th. The Pisan scientist leaves the Grand Duchy of Tuscany for the Republic of Venice, where he will spend eighteen highly productive years.

On August 13, of his relationship with Marina Gamba, Galileo's first daughter is born, baptised by the name of Virginia (1600-1634) in the church of San Lorenzo in Padua. The scientist casts the child's horoscope.

In a letter to Guidobaldo del Monte (1545-1607) dated November 19, Galileo states two assumptions: 1) the principle of pendular isochronism, according to which all of the oscillations of pendulums of equal length have the same duration, regardless of their amplitude and the size of the swinging mass; 2) the law of chords, according to which the time required for sliding down a vertical circle along each chord remains the same regardless of the length and slope of the plane. Both of these assumptions thus confirm that the motions of bodies descending along circular arcs always take place in equal periods of time.

On August 21 Galileo's third child, a son, is born. He is baptized in the parish of Santa Caterina, in Padua, with the name of his paternal grandfather Vincenzo (1606-1649).

On April 25 Galileo is enrolled in the Accademia dei Lincei. Federico Cesi (1585-1630), founder of the Accademia, proposes to name the marvellous instrument of observation "telescope" [from the Greek "tele" (distant) and "scopeo" (I see)]. In the months of April and May, Galileo observes not only the Medicean Planets but also sunspots. In early June he leaves Rome to return to Florence.

In the month of March the "Istoria e dimostrazioni intorno alle macchie solari" [History and demonstrations relating to sunspots] (Rome, 1613) is printed in Rome, under the aegis of the Accademia dei Lincei. Here Galileo disputes the priority of the discovery of this phenomenon with the Jesuit Christoph Scheiner (1573-1650).

On the fourth Sunday in Advent (December 21) the Dominican Tommaso Caccini (1574-1648), from the pulpit of the Basilica of Santa Maria Novella in Florence, preaches a sermon against Galileo and the Copernican doctrine, pointing out how the Holy Scriptures contradict the heliocentric theory. He also denounces mathematicians as bearers of heresy.

In late February the Congregation of Theologians of the Holy Office meets to decide whether to censor the opinion that the Earth's moves. The theory that the Sun occupies a central place in the universe is declared "stupid, absurd, and formally heretical"; the thesis that the Earth moves is deemed absurd from the philosophical point of view and erroneous in regard to faith. On February 26 Galileo, in the presence of Father Michelangelo Seghezzi, Commissar of the Holy Office, and two witnesses, is admonished by Cardinal Roberto Bellarmino (1542-1621) not to hold, teach or defend in any manner the Copernican doctrine. Galileo consents and promises to obey. On March 3, Bellarmino reports the admonition inflicted on Galileo to the Congregation of the Holy Office. On March 5, the Congregation of the Index suspends the "De revolutionibus orbium coelestium" (Nuremberg, 1543) by Nicolaus Copernicus (1473-1543) until it can be corrected by a specially appointed commission. On May 26, Bellarmino issues Galileo a statement specifying that the scientist "has not abjured in our hands nor in those of others here in Rome, nor in any other place known to us, any of his opinions or doctrines". On June 4, after a six months' stay in Rome, the scientist departs for Florence.

In early February the reviser, the Dominican Niccolò Riccardi (1585-1639), grants approval to print "Il Saggiatore" [The Assayer] (Rome, 1623). In addition to Federico Cesi (1585-1630), another member of the Accademia dei Lincei, Johann Faber (1574-1629), thoroughly revises Galileo's text a few days before printing. The work, published in late October under the aegis of the Accademia dei Lincei, is dedicated to the new Pope Urban VIII (1568-1644), risen to the papal throne on August 6. Today this work is generally considered to be Galileo's methodological manifesto and his literary masterpiece.

Galileo resumes his studies on the armature of magnets, begun during his years in Venice. On June 27 the Pisan scientist informs Cesare Marsili (1592-1633) that he has managed "to make a 6-ounce piece, that by its natural force does not support more than one ounce of iron, support by art 150 ounces". In replying to his letter, Marsili writes that he has heard that the Swiss Bartolomeo Sovero (c. 1577-1629) had managed to multiply its magnetic power sixty times, insignificant as compared to the one hundred and fifty times achieved by Galileo. A number of armed magnets are found today in the Istituto e Museo di Storia della Scienza, Florence.

The "Dialogo sopra i due massimi sistemi del mondo" [Dialogue on the two chief world systems] (Florence, 1632), a scientific and literary masterpiece, is published in Florence by the printer Giovanni Battista Landini. On February 22, Galileo presents this work to Grand Duke Ferdinando II de' Medici (1610-1670). But already by the middle of the year the first problems have arisen; it is rumoured that the "Dialogo" may be banned. On October 1, Galileo receives from the Florentine Inquisitor, Clemente Egidi, an injunction to appear in Rome before the Holy Office by the end of the month. Due to poor health, he postpones his departure several times. On December 30, Urban VIII (1568-1644) informs the Florentine Inquisitor that the Holy Office will send a commissar and physicians to Florence, at Galileo's expense, for the purpose of verifying the scientist's health. The Inquisitor is instructed to send Galileo to Rome as a prisoner in chains as soon as the physicians find him able to travel.

On December 1, 1633, the Congregation of the Holy Office allows Galileo to return to the villa "Gioiello", but forbids him to receive any persons with whom he might discuss scientific subjects. In the last days of the year he receives a visit from the Grand Duke of Tuscany Ferdinando II de' Medici (1610-1670).

On February 13, at the order of Pope Urban VIII (1568-1644), Galileo is visited by the Inquisitor of Florence and a physician. The Inquisitor reports to Cardinal Francesco Barberini (1597-1679) that he has found the scientist blind and "in such poor health that he seems more a cadaver than a living person". On February 25 the Holy Office authorizes him to move from the villa "Il Gioiello" to his Florentine house in Costa San Giorgio to treat his illness. In March he is informed of the decree that grants him pardon to move into the city, under certain conditions, to seek proper medical care. He is also granted permission to go on feast days to the nearest church, to confess and to take communion, but is forbidden to speak with other persons.

On January 8, at four o'clock in the morning, Galileo dies at the Villa il Gioiello at Arcetri. Vincenzo Viviani (1622-1703), in his "Racconto Istorico della Vita del Sig.r Galileo Galilei" [Historical account of the life of Galileo Galilei] describes his master's last moments as follows: "Overcome by slow fever and palpitations of the heart, after two months of illness that little by little consumed his spirits, on Wednesday, January 8 of 1641 "ab Incarnatione" [1642], at the hour of four in the night, at the age of seventy-seven years, ten months and twenty days, with philosophic and Christian firmness he rendered up his soul to its Creator, sending it, as he liked to believe, to enjoy and to watch from a closer vantage point those eternal and immutable marvels which he, by means of a fragile device, had brought closer to our mortal eyes with such eagerness and impatience."