The Greek astronomer Ptolemy’s Almagest was published around the year 145 in Alexandria, Egypt, while the Polish cleric Copernicus’s On the Revolutions (which we will simply call ‘Revolutions’ here) was published in 1543 from Nuremberg, Germany. Ptolemy’s vast synthesis was made possible by two thousand years of systematic observations carried out in Iraq, Syria, and Greece. Copernicus’s monumental analysis became possible thanks to fifteen hundred years of precise observations across India, China, Europe, and the Islamic world. In the five-thousand-year history of astronomy, these two books hold an exceptional place, as their social impact has been the greatest. Perhaps it is because Copernicus’s book was named ‘Revolutions’ that today the word ‘revolution’ has come to mean upheaval—the ‘Revolutions’ of Copernicus gave birth to the greatest scientific and social revolution in history. In this article, we will explore how, from the Almagest to the Revolutions, humans have tried to build a “working model” of the universe, and how the model of the Revolutions ultimately proved itself.