Can I offer my opposite opinion here? I think Ptolemy is one of the most important figures in the history of science. Not necessarily at the level of Newton or Kepler, but certainly on par with Tycho Brahe.

Today we know of Ptolemy because of the whole thing with Galileo and the Inquisition and his famous "E pur si muove". And also because of Copernicus. And Giordano Bruno burning on the stake. And since a good superhero story needs a villain, Ptolemy is cast in that role.

First, to disabuse anyone of any idea that Galileo was Batman and Ptolemy the Joker, I will link here the singular and incomparable blog post "The great Ptolemaic smackdown" [1]. I know, I know, it's late where you are, and you have to go to work tomorrow. But this is something that shows up on the internet about once a decade. Go and read it, and call in sick tomorrow. Or just bookmark it, and spend an afternoon over the weekend with a fine glass of wine and a fine piece of science writing.

Back to my argument, which is somewhat orthogonal to the linked blogpost.

Let's go back to the time of Ptolemy, which is also the times of Trajan, Hadrian and Marcus Aurelius. The Roman empire was at the pinnacle of its power. We are in the middle of a calm and prosperous period now known as Pax Romana. Culture is flourishing. It is the apogee of the Roman architectural revolution [1].

Yet science is nothing like the science of the 19th to 21st century. Today the bedrock of science is making falsifiable hypotheses and testing them. We also like when these hypotheses are based on simple laws. Such as Newton's laws.

But back them people just did not have the same concepts. The Greek culture (which continued under the Roman empire) had its shining pearl in Euclid. The neat edifice of axioms/proofs/theorems created by Euclid was a stunning breakthrough. Most likely it had its origins in Plato's axiomatic-like style of philosophy before him.

But the concept of systematic observation was missing. That was Ptolemy's phenomenal contribution. He collected the best astronomical observations until his time, and fit a certain mathematical theory to these observations. The theory (as we now know) was flawed. But the method was a stupendous advance.

Through no fault of Ptolemy, the Roman empire entered a period of decline. For a thousand years no person of the caliber of Ptolemy put the effort to gather more precise astronomical observations, and fit a better theory to them. Instead, people copied over and over his tabulated observations, inserting errors in the process. The first astronomical tables to surpass Ptolemey's ones were the Alfonsine tables, created about 1100 years after him.

After that, we finally enter the modern era with the tables produced by Tycho Brahe and Jonathan Kepler and published under the name as the Rudolphine tables in 1627.

Think about this for a moment: the first improvement over Ptolemy's tables took about one millennium, and the second another half a millennium. After which science entered an exponential explosion that continues to this day.

What happened then, was perfectly natural. If someone sets a record that stands for a thousand years, humans, being what they are, will naturally lionize that person. Eventually his every recorded sentence will acquire the status of an absolute theorem. People will not dare to contradict him. And this can stop science in its tracks.

But is that any of Ptolemy's fault?

Compare Ptolemy with Tycho Brahe, who was followed in quick succession by Kepler and Newton. What if Ptolemy had a younger peer of his caliber, like Brahe fortuitously had Kepler? There is a chance that the world could have had a scientific revolution one thousand years before it actually had it.

[1] https://en.wikipedia.org/wiki/Roman_architectural_revolution
[2] http://tofspot.blogspot.com/2013/08/the-great-ptolemaic-smac...
[3] https://en.wikipedia.org/wiki/Alfonsine_tables
[4] https://en.wikipedia.org/wiki/Rudolphine_Tables