deletions | additions       diff --git a/Lecture_4_Guest_lecture_by__.md b/Lecture_4_Guest_lecture_by__.md  index 4831996..1b3f772 100644  --- a/Lecture_4_Guest_lecture_by__.md  +++ b/Lecture_4_Guest_lecture_by__.md 
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  Discussion of Little Ice Age and recursive Plague.     Discussion of how skilled workers who invented things, who had "human capital", not capital" (not  fat old men doing mathematics mathematics/accounting  in London, London),  were the active players in the Industrial Revolution.