Comment by jmalicki
16 hours ago
It's a long arc, and as sibling comments say, there are many books about it.
The elites being able to capture some of it was what allowed for science and the enlightenment to happen, which eventually led to the technology that inspired the industrial revolution.
The big picture was it was the beginning of compound interest. This was a many step process over hundreds of years.
The events happened, but the mechanisms are subject to debate. Every school of economic thought has strong opinions on this time period. You've actually listed a source that contradicts your original argument (which came from where, out of curiosity?)
Basically, one common version is 'pro-elite' and blames the stagnation prior to this period on 'Malthusian dynamics' (over population beyond the productivity of the land). Another version is 'anti-elite' and blames the stagnation on the capture of all surplus by the landowning elite (who are not motivated to invest it other than the bare necessity to maintain status quo).
While there is considerable room for nuance and disagreement, Malthus is considered largely discredited by modern economics. As the population increased, so did the productivity of the land. Regardless, the fact people lived bare subsistence lives under feudalism does not imply the max population had been reached - they are still paying excess as rent. Peasants paid 1/2 their crop in rent, consumed 1/4 and replanted a 1/4 (crude approximation). This is very similar btw to modern US - there are 100M renters and the median rental household pays 50% of gross income to rent + tax.
Compound interest and capital investments predate the medieval period by thousands of years. There are cuneiform tablets documenting these kinds of financial arrangements.
'AFAIK the leading theory is that without the massive shock from population decline due to the bubonic plague, that surplus would have never existed to begin with, so how it was allocated would have been moot.' This is highly dubious/contentious.