According to Inherit the Wind, why exactly does a society need to progress? How would it progress? Also, what do you think is the theme of this...

Let me offer a counterpoint, which may help in formulating your thoughts. In particular I want to challenge the notion that there will always be progress. I think we have been influenced by Darwin's theory of evolution for too long. So, let me begin with a question:

How does one know that there will always be progress? Does not history shows that there are times of stagnation and regression? For example, all empires rise and fall, certain things are learned, forgotten and relearned. Some things may have been forgotten and never relearned. As Peter Berger, the sociologist, says, “It is also possible that there was a secret conclave of Aztec priest who knew something we have not even dreamed of – and that this truth perished with them, never to be recovered.” More importantly, how should one even define progress? In the least, one should question the notion of continual progression.