I don't understand the meaning of the word "study" in this sentence: It was among the most placid, a study in harmony and prosperity. Could someone kindly tell me what it means here?

Here is the context:
"For the first half of the twentieth century, Europe was the most turbulent region
on earth, convulsed by war, economic crisis, and social and political conflict. For the
second half of the century, it was among the most placid, a study in harmony and
prosperity. What changed?"

See a translation

I agree with all of that, and here is how I think of it.

Imagine that a philosopher had closely studied prosperity and harmony, and that he decided that Europe in the second half of the 20th century was an excellent example of that condition. If other people wanted to understand prosperity, he would recommend that they study Europe to understand how it works.

That's the sense of "study" here.

It is either:
1. Something specifically created as a pure example for others to study
2. Something representing an excellent example, which others can study

For example in business schools they often use case studies to illustrate various topics using real situations.