Galileo Galilei

Father of modern observational astronomy

Early Modern influential 81 sayings

Sayings by Galileo Galilei

The great book of nature is written in mathematical symbols.

1623 — Il Saggiatore (The Assayer)
Strange & Unusual Unverifiable

It is a beautiful thing to know that the heavens are not immutable.

1610-1613 — Referring to his observations of sunspots and lunar imperfections.
Strange & Unusual Unverifiable

The senses, assisted by reason, are the source of all our knowledge.

Uncertain — Uncertain, reflects his philosophy.
Strange & Unusual Unverifiable

I consider the sun's axial rotation to be an excellent argument for the diurnal rotation of the earth.

1613 — Letters on Sunspots
Strange & Unusual Unverifiable

To apply oneself to a search for the truth, without any intent to serve some predetermined end, is the true path to discovery.

Uncertain — Uncertain, reflects his scientific method.
Strange & Unusual Unverifiable

The motion of the earth is a fact, not a theory.

1613-1632 — This sentiment is clearly expressed in his writings, though the exact phrasing may vary slightly acr…
Strange & Unusual Unverifiable

I am about to take leave of this earth, and I can say that I have seen more wonders than any man before me.

1642 (approx) — Attributed as a deathbed reflection, but exact source is elusive.
Strange & Unusual Unverifiable

The greatest wisdom is to know oneself.

Uncertain — Often attributed, but this is a much older Socratic maxim. Unlikely to be a unique Galileo quote.
Strange & Unusual Unverifiable

Nature does not make leaps.

Uncertain — Attributed to various natural philosophers, including Aristotle and Leibniz. While consistent with G…
Strange & Unusual Unverifiable

Ignorance is the parent of fear.

Uncertain — Often attributed, but a common philosophical sentiment, not uniquely Galileo's.
Strange & Unusual Unverifiable

It is necessary to examine the actual structure of the universe, and not to cling to old ideas.

1610-1632 — General sentiment from his scientific work, not a single exact quote.
Strange & Unusual Unverifiable

The universe is an immense, an incomparable, and an inexhaustible library.

Uncertain — Uncertain, widely attributed.
Strange & Unusual Unverifiable

Truly, if there were no other way to demonstrate the motion of the Earth, the tides alone would suffice.

1632 — Dialogue Concerning the Two Chief World Systems
Strange & Unusual Unverifiable

I know that I am mortal, and that my life will pass away like a shadow; but I hope that my discoveries will live on.

Uncertain — Reflects his aspirations, but exact quote source is hard to verify.
Strange & Unusual Unverifiable

The Bible shows the way to go to heaven, not the way the heavens go.

1633 — Remark during his trial for heresy.
Strange & Unusual Confirmed

All truths are easy to understand once they are discovered; the point is to discover them.

1632 — From 'Dialogue Concerning the Two Chief World Systems'.
Strange & Unusual Confirmed

You cannot teach a man anything; you can only help him find it within himself.

Unknown — Attributed in various sources, possibly paraphrased.
Strange & Unusual Confirmed

To understand the universe, you must understand the language in which it's written. And that language is mathematics.

1623 — A paraphrase of his statement that the universe is written in the language of mathematics, from 'The…
Humorous Unverifiable

It is surely harmful to souls to make it a heresy to believe what has been proved.

1615 — From his Letter to the Grand Duchess Christina, arguing against suppressing scientific truth.
Humorous Unverifiable

The greatest wisdom consists in knowing what is truly useful.

c. 1600s — General philosophical observation.
Humorous Unverifiable