Galileo Galilei 1564 – 1642
Galileo Galilei (1564 – 1642) was an Italian philosopher of the Modern era, associated with Renaissance and Early Modern Philosophy.
Galileo Galilei was an Italian astronomer, physicist, and philosopher of science whose work helped to inaugurate the scientific revolution. He improved the telescope and used it to observe the moons of Jupiter, the phases of Venus, and the rugged surface of the Moon, marshalling evidence for the Copernican system. He defended the autonomy of natural inquiry from theological authority and articulated a mathematical conception of nature that became foundational for modern physics. Tried by the Roman Inquisition in 1633, he spent his last years under house arrest, where he completed his Discourses on Two New Sciences.
Galileo Galilei was born in 1564 in Pisa, the son of the lutenist and music theorist Vincenzo Galilei. He entered the University of Pisa as a medical student in 1581, drifted into mathematics, and left without a degree. After private teaching in Florence and Siena he secured the chair of mathematics at Pisa in 1589 and moved in 1592 to the better-paid chair at Padua, where he remained for eighteen of the most productive years of his life.
His telescopic discoveries — the moons of Jupiter, the phases of Venus, the mountains of the moon, the resolution of the Milky Way into stars — were announced in the Sidereus Nuncius in 1610 and brought him to Florence as court mathematician to the Medici. The major works that followed are the Letters on Sunspots (1613), The Assayer (1623), the Dialogue Concerning the Two Chief World Systems (1632), and the Two New Sciences (1638). The Dialogue led to his condemnation by the Roman Inquisition in 1633 and to house arrest at Arcetri for the rest of his life.
Galileo placed mathematical demonstration and controlled observation at the heart of natural philosophy, established the law of falling bodies and the principle of inertia, and gave decisive empirical support to the Copernican system. He went blind in his last years and died at Arcetri in 1642.
Key facts
- Nationality
- Italian
- Era
- Modern
- Movements
- Renaissance, Early Modern Philosophy
Selected quotes
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Attributed to Galileo Galilei:
“Philosophy is written in this grand book, the universe, which stands continually open to our gaze. But the book cannot be understood unless one first learns to comprehend the language and read the letters in which it is composed. It is written in the language of mathematics.”
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“I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use.”
Letter to the Grand Duchess Christina -
Attributed to Galileo Galilei:
“All truths are easy to understand once they are discovered; the point is to discover them.”
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“In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.”
sì perché l'autorità dell'opinione di mille nelle scienze non val per una scintilla di ragione di un solo, sì perché le presenti osservazioni spogliano d'autorità i decreti de' passati scrittori, i quali se vedute l'avessero, avrebbono diversamente determinato. -
Attributed to Galileo Galilei:
“Measure what is measurable, and make measurable what is not so.”
Galileo Galilei by topic
Frequently asked about Galileo Galilei
- When did Galileo Galilei live?
- Galileo Galilei was born in 1564 and died in 1642.
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- Galileo Galilei was an Italian philosopher of the Modern era.
- What philosophical movements is Galileo Galilei associated with?
- Galileo Galilei was associated with Renaissance and Early Modern Philosophy.
- What was Galileo Galilei known for?
- Galileo Galilei was an Italian astronomer, physicist, and philosopher of science whose work helped to inaugurate the scientific revolution.
- How many quotes are attributed to Galileo Galilei?
- There are 16 attributed quotations from Galileo Galilei in the 1001Philosophers collection, organized by topic.
Quotes that are not actually from Galileo Galilei
These lines are widely circulated as Galileo Galilei, but they do not appear in Galileo Galilei's works. Each entry below identifies the actual source.
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“It is only in order to shield your ignorance that you put the Lord at every turn to the refuge of a miracle.”
This quote is commonly attributed to philosophers but its actual source is uncertain or unverified in the standard reference works. Wikiquote's note on this attribution: Giorgio de Santillana attributed this remark to the Dialogue in The Crime of Galileo (1955), but it does not appear there. A vaguely similar exchange appears in the Fourth Day of the Dialogue , when Salviati asks Simplicio why he resorts to a miracle to explain the tides, if they might be explained
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“Mathematics is the key and door to the sciences.”
This quote is commonly attributed to philosophers but its actual source is uncertain or unverified in the standard reference works. Wikiquote's note on this attribution: As quoted in Building Fluency Through Practice and Performance (2008) by Timothy Rasinski and Lorraine Griffith, p. 64, but in fact a quotation by Roger Bacon : Et harum scientiarum porta et clavis est Mathematica , "And of these sciences the door and key is mathematics", from Bacon's Opus Majus (12
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“Measure what is measurable, and make measurable what is not so.”
This quote is commonly attributed to philosophers but its actual source is uncertain or unverified in the standard reference works. Wikiquote's note on this attribution: The quote is widely misattributed to Galilei, but is actually from two French scholars, Antoine-Augustin Cournot and Thomas-Henri Martin. See "Der messende Luchs: Zwei verbreitete Fehler in der Galilei-Literatur" by Andreas Kleinert in "NTM Zeitschrift für Geschichte der Wissenschaften, Technik und