Of civilisation and nation-building... in accelerated and simplified fashion.
Basically, the episode illustrated how a nation inevitably has to become pragmatic (e.g. prioritizing water supply over preservation of history) and learn how to be rational with distribution of resources or otherwise face economic and societal downfall. Also, the importance of a leader's decisions: you get carried away with pouring resources into something, you lose something in return. And more often than not, the consequences are very heavy.
Jintai, you always light up my day~