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There’s an old belief that truth will always overcome error. Alas, history tells us something different. Without someone to fight for it, to put error on the defensive, truth may languish. It may even be lost, at least for some time. No one understood this better than the renowned Italian scientist Galileo Galilei.

It is easy to imagine the man who for a while almost single-handedly founded the methods and practices of modern science as some sort of Renaissance ivory-tower intellectual, uninterested and unwilling to sully himself by getting down into the trenches in defense of science. But Galileo was not only a relentless advocate for what science could teach the rest of us. He was a master in outreach and a brilliant pioneer in the art of getting his message across.

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Today it may be hard to believe that science needs to be defended. But a political storm that denies the facts of science has swept across the land. This denialism ranges from the initial response to the COVID-19 pandemic to the reality of climate change. It’s heard in the preposterous arguments against vaccinating children and Darwin’s theory of evolution by means of natural selection. The scientists putting their careers, reputations, and even their health on the line to educate the public can take heart from Galileo, whose courageous resistance led the way.

STAND UP FOR SCIENCE: Participants in the annual March for Science make Galileo proud, protesting those in power who have devalued and eroded science. (Above: Washington, D.C., 2017)bakdc / Shutterstock
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A crucial first step, one that took Galileo a bit of time to take, was to switch from publishing his findings in Latin, as was the custom for scientific writings at the time, to the Italian vernacular, the speech of the common people. This enabled not just the highly educated elite but anyone who was intellectually curious to hear and learn about the new scientific work. Even when risking offense (which Galileo never shied away from)—for instance, in responding to a German Jesuit astronomer who disagreed with him on the nature of sunspots (mysterious dark areas observed on the surface of the sun)—Galileo replied in the vernacular, because, as he explained, “I must have everyone able to read it.” An additional motive may have been that Galileo wanted to ensure that no one would somehow distort the meaning of what he had written.

Galileo also understood that while the Church had the pomp and magic of decades of art and music, science had the enchantment of a new invention—the telescope. Even he wasn’t immune to its seductive powers, writing in his famous booklet The Sidereal Messenger: “In this short treatise I propose great things for inspection and contemplation by every explorer of Nature. Great, I say, because of the excellence of the things themselves, because of their newness, unheard of through the ages, and also because of the instrument with the benefit of which they make themselves manifest to our sight. “ And that gave him his second plan for an ambitious outreach campaign.

With alternative facts acting like real facts, there are Galileo’s heirs, throwing up their hands and attempts to make lies sound like truth.

What if he could distribute telescopes (together with detailed instructions for their use and his booklet about the discoveries) all across Europe, so that all the influential people, that is, the patrons of scientists—dukes and cardinals, could observe with their own eyes far out into the heavens. They would see the stunning craters and mountains that cover the surface of the moon, four previously unseen satellites of Jupiter, dark spots on the surface of the sun, and the vast number of stars that make up the Milky Way.

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But telescopes were both expensive and technically difficult to produce. Their lenses had to be of the highest quality, to provide both the ability to see faint objects and high resolution. “Very fine lenses that can show all observations are quite rare and, of the more than sixty I have made, with great effort and expense, I have only been able to retain a very small number,” Galileo wrote on March 19, 1610. Who would front the cost of such a monumental and risky project?

Today the papacy is arguably the single most influential and powerful religious institution in the world. But its power is mostly in the moral and religious realms. In Galileo’s time, the papacy was a political power of significance, gobbling up failed dukedoms elsewhere, merging them into what became known as the “papal states.” The persons with the greatest interest in appearing strong in front of the papacy were the heads of neighboring states at the time.

So it is not surprising that Galileo presented his grandiose scheme to the Tuscan court and the Grand Duke Cosimo II de’ Medici. Nor is it surprising that Cosimo agreed to finance the manufacturing of all the telescopes. On his own, he also instructed the Tuscan ambassadors to all the major European capitals to help publicize Galileo’s discoveries. In doing so he tied the House of Medici, ruler of the foundational city of the Renaissance, Florence, to modern science. A win-win for both the Grand Duke and Galileo.

Last, Galileo instinctively understood what modern PR specialists refer to as the “quick response.” He did not let even one unkind word be said about his discoveries without an immediate reply. And his pen could be sharp.

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For example, the Jesuit mathematician Orazio Grassi (hiding behind the pseudonym of Sarsi) published a book entitled The Astronomical and Philosophical Balance, in which he criticized Galileo’s ideas on comets and on the nature of heat. In it, Grassi mistakenly thought that he would strengthen his argument by citing a legendary tale about the ancient Babylonians cooking eggs by whirling them on slings.


Galileo responded with a stupendous piece of polemic literature entitled The Assayer, in which he pounced on this fabled story like a cat on a mouse.

“If Sarsi wishes me to believe, on the word of Suidas [a Greek historian], that the Babylonians cooked eggs by whirling them rapidly in slings, I shall believe it; but I shall say that the cause of this effect is very far from the one he attributes to it,” he wrote. “ To discover the true cause, I reason as follows: ‘If we do not achieve an effect which others formerly achieved, it must be that we lack something in our operation which was the cause of this effect succeeding, and if we lack one thing only, then this alone can be the true cause. Now we do not lack eggs, or slings, or sturdy fellows to whirl them, and still they do not cook, but rather cool down faster if hot. And since we lack nothing except being Babylonians, then being Babylonian is the cause of the egg hardening.’”

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Galileo understood what modern PR specialists refer to as the “quick response.” He did not let one unkind word go without an immediate reply.

Did Galileo’s efforts save science from being cast aside perhaps for decades, even centuries? Unfortunately, not quite. The trial in which he was convicted by the Inquisition for “vehement suspicion of heresy” exerted a chilling effect on progress in deciphering the laws governing the cosmos. The famous French philosopher and scientist René Descartes wrote in a letter: “I inquired in Leiden and Amsterdam whether Galileo’s World System was available, for I thought I had heard that it was published in Italy last year. I was told that it had indeed been published, but that all the copies had immediately been burnt in Rome, and that Galileo had been convicted and fined. I was so astonished at this that I almost decided to burn all my papers, or at least to let no one see them.”

I suspect that there are still too few of us who can tell exactly what Galileo discovered and why he is such an important figure to the birth of modern science. But around the world, in conversations as brittle as today’s politics, with alternative facts acting like real facts, there are Galileo’s heirs, throwing up their hands at such attempts to make lies seem like the truth and worse, the truth like a lie, responding with just four words: “And yet it moves.”

Galileo may have never really uttered these words. He surely didn’t say that phrase in front of the Inquisitors—that would have been insanely dangerous. But whether the motto came first from his own mouth, that of a supporter whom he met during the years the Church put him under house arrest after his trial, or a later historian, we know one thing for sure. That motto represents everything Galileo stood for. It conveys the clear message of: In spite of what you may believe, these are the facts! That science won at the end is not solely because of the methods and rules that Galileo set out for what we accept to be true. Science prevailed because Galileo put his life and his personal freedom on the line to defend it.

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Mario Livio is an astrophysicist and author. His new book is Galileo: And the Science Deniers.

Lead image: Mario Breda / Shutterstock

This article first appeared in our “Outbreak” issue in May 2020.

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