Feeny Road: Why not Galileo Day?

Portrait of Galileo by Justus Sustermans

The other day we rightfully celebrated the

anniversary of the births Abraham Lincoln as well as Charles Darwin, both born on February 12, 1809. As America’s greatest statesman, Lincoln led the fight to maintain the Union and freed nearly four million slaves; while Darwin, grandson of famed enlightenment thinker Erasmus Darwin, became the world famous evolutionary theorist, naturalist, geologist, biologist, and author of (among others) On the Origins of Species, and one of the great thinkers of the 19th century.

The celebration of these two giants both born on the same day in 1809, oftentimes overshadows by only a few days the birth of yet another of the great minds in our shared human history, Galileo Galilei, born in Pisa, Italy on today’s date in 1564 (d. January 8, 1642).

Equally considered the father of modern astronomy, the father of modern physics, and the father of modern science, Galileo taught mathematics, geometry, and astronomy. His work included observing how the swing of a pendulum does not depend on the arc (the isochronism) which led to the development of the pendulum clock. Galileo questioned the Aristotelian approach to physics and the belief that heavier objects fall faster through a medium than lighter ones and proved that all objects regardless of their density, fall at the same rate in a vacuum (his findings were published many years after his death in his book, De Motu or On Motion). Galileo invented the pump, the hydrostatic balance, the thermoscope, a precursor to the thermometer, and most famous of all, in 1609 he invented the telescope, using it to prove the Copernican theory—the idea that the earth and planets revolved around the sun, as opposed to the Ptolemaic geocentric (and Biblical) idea which held that the sun revolved around the earth. In 1610, Galileo published Starry Messenger (Sidereus Nuncius) and described observations he had made with his telescope including discovering four moons of Jupiter.

For years Galileo had written in support of the Copernican theory and how the earth revolved around the sun. Indeed, as early as 1616 the Catholic Church had warned Galileo to, "abandon completely the…opinion that the sun stands still at the center of the world and the earth moves, and henceforth not to hold, teach, or defend it in any way whatever, either orally or in writing; otherwise the Holy Office would start proceedings against him.”

Dialogue Concerning
Two Chief World Systems

As is often the case with genius, Galileo remained steadfast and ignored Church admonition to "be silent" and on February 22, 1632, published Dialogue Concerning the Two Chief World Systems. As the titled implied, Galileo's work took the form of a dialogue or discussion surrounding the Ptolemaic and Copernican systems. Galileo began his famous by telling the reader that: “since bitter death has deprived Venice and Florence [Ptolemy and Copernicus] of those two great luminaries in the very meridian of their years, I have resolved to make their fame live on in these pages, so far as my poor abilities will permit, by introducing them as interlocutors in the present argument.”

Within his book Galileo presented three characters:

Salviati, a proponent of the Copernican theory who postulated the idea that (among other things) the earth revolved around the Sun and Galileo described as possessing “…a sublime intellect which fed no more hungrily upon any pleasure than it did upon fine meditations;"

Simplicio (oftentimes thought of as a simpleton) who supported Ptolemaic model which held that the earth was fixed within the universe, did not move, and that sun and all heavenly bodies revolved around it; and finally,

Sagredo, “…a man of noble extraction and trenchant wit,” who represents an honest broker striving to hearing all sides."

Having published his book, Galileo was charged "...for holding as true the false doctrine taught by some that the sun is the center of the world and motionless and the earth moves even with diurnal motion; for having disciples to whom you taught the same doctrine; for being in correspondence with some German mathematicians about it; for having published some letters entitiled On Sunspots, in which you explained the same doctrine as true; for interpreting Holy Scripture according to your own meaning in response to objections based on Scripture which were sometimes made to you; and whereas later we received a copy of an essay in the form of a letter, which was said to have been written by you to a former disciple of yours and which in accordance with Copernicus's position contains various propositions against the authority and true meaning of Holy Scripture."

For teaching that that the "sun is the center of the world and motionless is a proposition which is philosophically absurd and false, and formally heretical, for being explicitly contrary to Holy Scripture;" and that "the earth is neither the center of the world nor motionless but moves even with diurnal motion is philosophically equally absurd and false, and theologically at least erroneous in the Faith, on June 22, 1633, Galileo was found guilty of heresy.

Imagined Galileo on trial,
pushing the Bible away

Galileo was convicted of:

“[vehemently suspected]…heresy, namely of having held and believed a doctrine which is false and contrary to the divine and Holy Scripture: that the sun is the center of the world and does not move from east to west, and the earth moves and is not the center of the world, and that one may hold and defend as probable an opinion after it has been declared and defined contrary to Holy Scripture.”

As a verdict of heresy by the Catholic Church oftentimes lead to being burned at the stake, the 70 year-old Galileo recanted his teachings:

“…with a sincere heart and unfeigned faith I abjure, curse, and detest the above-mentioned errors and heresies, and in general each and every other error, heresy, and sect contrary to the Holy Church; and I swear that in the future I will never again say or assert, orally or in writing, anything which might cause a similar suspicion about me; on the contrary, if I should come to know any heretic or anyone suspected of heresy, I will denounce him to this Holy Office, or to the Inquisitor or Ordinary of the place where I happen to be.”

Galileo’s book was formally banned and while he was sentenced to prison, the sentenced was commuted to house arrest for the rest of his life. Popular legend has it that upon recanting his teachings, Galileo defiantly muttered e pur, si muove - "even so, it does move" (oftentimes translated to “and yet it moves”) under his breath.

360 years later, on October 31, 1992, Pope John Paul II addressed the Pontifical Academy of Sciences noted how the:

“…brilliant physicist and by relying on different arguments, Galileo, who practically invented the experimental method, understood why only the Sun could function as the centre of the world, as it was then known, that is to say as a planetary system. The error of the theologians of the time, when they maintained the centrality of the Earth, was to think that our understanding of the physical world's structure was, in some way, imposed by the literal sense of the Sacred Scripture. Let us recall the celebrated saying attributed to Baronius: "Spiritui Sancto mentem fuisse nos docere quomodo ad coelum eatur non quomodo coelum gradiatur" [The Holy Spirit shows us how to go to heaven, not how the heavens go.]…There exist two realms of knowledge, one which has its source in Revelation and one which reason can discover by its own power.”

Perhaps we should add Galileo Day to our calendar?

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