A thought-provoking post today, @slowwalker.

It's very evident that the pagoda from the Goryeo dynasty is inferior and crude in workmanship compared to the Shilla style.

I suspected that there was a simple explanation because I knew from my study of art and art history that progress in technique is not a straight line development - at times, it's more a case of one step forward and two steps back.

Sometimes the decline can come about because of political forces that change the society - for example,in the the west after the decline of the Roman empire, western Europe's culture and learning began to deteriorate. That's an aspect you might want to look at.

But, sometimes it's a matter of emphasis. The Shilla dynasty concentrated on stone - the Goryeo dynasty developed beautiful ceramic pottery called Celadon which was a technological breakthrough in Korean ceramics.

So, you see,@slowwalker, some aspects of society seem progressive and others regressive depending on emphasis.

When I taught English Literature I saw the same effect in students' writing - emphasis on non-print media such as computers and videos eroded students' writing and reading abilities.

Thank you for posing the question today, my friend - it caused me to seek out an answer to many things :)