Subject:  Metacognition – Copernicus’ Definition of True Knowledge

Event:  Birthday of Nicolaus Copernicus, 1473

Today is the birthday of Nicolaus Copernicus, a man who not only changed the world as we know it, but also the universe.  

Nicolaus Copernicus (Wikimedia Commons)

Born in Poland in 1473, Copernicus was both a polyglot and a polymath.  He spoke Latin, German, Polish, Greek, and Italian.  In addition to holding a doctorate in canon law, he was also a physician, mathematician, classics scholar, translator, governor, diplomat, and economist.  Today, we know him best as the astronomer who challenged the orthodox belief that Earth was the center of the universe.  Fifteen-hundred years after the ancient Greek astronomer Ptolemy established his theory that the planets, the sun, and the stars revolved around a stationary Earth, Copernicus presented his revolutionary theory.  He claimed that not only did the Earth rotate on its axis, but also that Earth and the other planets revolved around the sun.  Copernicus’ work in astronomy was the quintessential achievement of the Renaissance, totally transforming mankind’s view of the universe and paving the way for future work by Galileo, Kepler, and Newton.

A true man of science and of learning, Copernicus embodied the Renaissance ideals of searching for knowledge and challenging conventional wisdom. His opus On the Revolution of the Celestial Spheres was published in 1543, the same year he died (1).

One quotation that typifies Copernicus’ scientific approach is one that uses simple terms to express a profound insight:

To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge.

Today cognitive psychologists sum up Copernicus’ insight using a single term: metacognitionMeta is Greek for “about,” and cognition is Latin for “to know.” Metacognition, therefore, is “thinking about thinking.”  More than just being aware that we think, metacognition is the process of monitoring our own thinking.

As Copernicus reminds us, metacognition is not just what we know, it is also being aware of what we don’t know, as well as being aware of the ways we sometimes delude ourselves.  To understand the ways we think best and the ways we fall short of sound thinking, we should always keep in mind the relationship between both knowledge and ignorance.  

Notice, for example, how the following wise voices from the past express this relationship:

-Real knowledge is to know the extent of one’s ignorance.  –Confucius

-The greatest obstacle to discovering the shape of the earth, the continents and the ocean was not ignorance but the illusion of knowledge. –Daniel J. Boorstin

-The only good is knowledge and the only evil is ignorance. — Socrates

-The recipe for perpetual ignorance is: Be satisfied with your opinions and content with your knowledge. — Elbert Hubbard

-To be conscious that you are ignorant is a great step to knowledge. — Benjamin Disraeli

-The beginning of knowledge is the discovery of something we do not understand. — Frank Herbert

In the book Make It Stick, the authors discuss one specific learning strategy that employs metacognition to help learners be more productive and more efficient in their study.  The strategy is called retrieval practice, and recent studies have documented that this strategy is much more effective than rereading a text, highlighting a text, or even reviewing notes.

The key aspect of retrieval practice is self-quizzing or testing.  When reading a text or listening to a lecture, therefore, the student should generate questions for self-testing.  Once the student has finished reading or listening, he or she should use the questions to recall and recite out loud the facts, concepts, or events from memory, without using the book or notes for reference.  The basic premise of retrieval practice is that learning that sticks is learning that is effortful.  Furthermore, the effortful act of retrieving knowledge from memory strengthens the memory, increasing the likelihood that knowledge will stay in long-term memory.  Like walking an unfamiliar path through the woods, the more you travel the path, the more confidence you have in remembering your way without getting lost.  Retrieval practice also decreases the likelihood that students will delude themselves into believing they know what they don’t know. Since the strategy requires that students recite answers aloud without notes, they are able to exercise good metacognition by clearly determining what they know and what they don’t quite know yet (2).

Recall, Retrieve, Recite, Ruminate, Reflect, Reason:  What is retrieval practice and how does it relate to metacognition?

Challenge – What Do You Know?

How can you apply retrieval practice to increase your metacognition?  Select an article or short story that you have not read before.  As you read the passage, write down three questions based on the key ideas you’re reading.  When you finish the reading, put the passage away, and attempt to answer each of your questions by reciting the answers out loud.  As you answer each question, rate your level of confidence with your answer on a scale of 1 to 10 (10 being you feel highly confident; 1 being you need to look back at the passage to answer).  Once you have finished, take a moment to reflect on the strategy.  How did it feel to answer out loud?  Do you feel like this strategy will work for you in the future? 


1-”Nicolaus Copernicus” – New Mexico Museum of Space History

2-Brown, Peter C., Henry L. Roediger III, Mark A. McDaniel.  Make It Stick:  The Science of Successful Learning.  Cambridge, Mass.:  Harvard University Press, 2014.


Subject:  Conventional Wisdom – the Discovery of Jupiter’s Moons

Event:  Galileo Galilei Discovers the Moons of Jupiter, 1610

In 1610, the Italian astronomer Galileo Galilei (1564-1642) made a discovery that changed not just the world but also the heavens.  Although Galileo did not invent the telescope, he did make significant improvements that increased its magnification.  He was also among the first to turn the telescope to the night sky and record observations of the stars.  This is exactly what he was doing on the night of January 7, 1610, when he observed what he first thought were three fixed stars near Jupiter.  Further examination revealed that instead of stars, he was seeing natural satellites orbiting Jupiter.  Later he discovered a fourth satellite.  Today we know these satellites as Callisto, Europa, Ganymede, and Io:  the Galilean Moons of Jupiter. 

Galileo’s discovery was much more significant than just discovering the moons of a distant planet.  What he saw in his telescope called into question the conventional wisdom of the geocentric theory, which said that all celestial bodies rotated around the Earth, the center of the universe. Geocentrism dated back to ancient astronomy and the Old Testament.  As a Catholic, Galileo realized that his discovery was at odds with the teachings of the powerful Roman Catholic Church.  

Years earlier, in 1514, the Polish monk and mathematician Copernicus had theorized the heliocentric theory, which put the Sun not the Earth at the center of the universe.  Copernicus did not have a telescoper, however, so his theory lacked the kind of solid proof that would challenge the orthodoxy of the geocentric model.   Galileo’s discoveries provided the concrete proof that confirmed Copernicus’ theory.

Cristiano Banti’s 1857 painting Galileo facing the Roman Inquisition (Wikipedia)

In 1616, the Catholic Inquisition rejected heliocentrism and ordered Galileo to abandon his claims, but he refused to remain quiet.  In 1632, he published “Dialogue Concerning the Two Chief World Systems,” where he juxtaposed the arguments for the geocentric universe and the heliocentric universe.  After the publication of his book, Galileo was charged with heresy and tried by the Inquisition in Rome.  In June 1633, he was put under house arrest and his publications were banned. On June 22, 1633, Galileo was found guilty of heresy and sentenced to life imprisonment.  Ordered to kneel, he was directed to read a statement recanting his theory.  

Probably the most famous quotation attributed to Galileo is a brief statement that he supposedly made at the end of his trial:  “Eppur si muove” (“And yet it moves).”  This statement — which is probably more legend than fact — would be a contradiction of the Catholic Church’s view of the Earth that stands still at the center of the universe.  Even though under house arrest, Galileo continued his scientific work until his death in 1642.

Today his views have been vindicated, and not only is he seen as the father of astronomy, but he is also seen as the father of modern science (1).

In 1992, 350 years after the Catholic Church condemned Galileo, Pope John Paul II issued a formal statement admitting that the church was wrong:  the Earth does move (2).

Recall, Retrieve, Recite, Ruminate, Reflect, Reason:  How did Galileo’s discovery of Jupiter’s moons upend conventional wisdom?

Challenge – Where the Experts Were Wrong:  Obviously we know from history that the Catholic Church was wrong about the geocentric universe.  Research another example from history of where the experts were wrong.


1-Levesque, Paul. “Skywatch:  Galileo’s Discovery of the Moons of Jupiter Disrupted Conventional WisdomQuad-City Times. 4 Oct. 2020.

2-Cowell, Alan.  “After 350 Years, Vatican Says Galileo Was Right: It Moves.” New York Times 31 Oct. 1992.