6 ideas
Since about 1800, real income per person in the rich countries has risen by a factor of roughly 30, and by 10 even counting the world's poorest. This leap is too large to be explained by standard mechanisms like trade, investment, or exploitation, since those produce gains of percentages, not multiples. So the question of why it happened needs an explanation of a different order.
Piling up capital, whether physical, human, or from slavery and empire, runs into diminishing returns. Many earlier societies saved and invested heavily without taking off. Capital was a dependent variable that followed innovation. It was not the cause.
Property rights and rule of law existed long before 1800 in many places that did not enrich. Formal rules only work when the surrounding ethics and conversation give people reason to honor them. Institutionalist explanations therefore miss the prior cause: how a society talks about and values commercial activity.
The bourgeois deal is an implicit social bargain. In the third act, competition and imitation spread the gains so that everyone becomes rich. Accepting this deal, rather than suppressing innovators out of envy or tradition, is what unleashed mass betterment.
How people talk about merchants, profit, and invention changes what the ambitious choose to do. When commerce is sneered at, talent flows to war, church, and court. When the talk honors trade, talent flows into betterment. Changes in dignity and persuasion are therefore real economic causes, not mere reflections of material conditions.
From about 1600 to 1800, first in Holland and then in Britain, a shift in public opinion began treating merchants and inventors as respectable instead of contemptible. Accidents of the Reformation, Dutch revolt, and English political settlements spread ideas of liberty and equal dignity for ordinary people. The places where this reappraisal happened first are the places where sustained innovation-led growth first began.