deletions | additions       diff --git a/Lecture_4_Guest_lecture_by__.md b/Lecture_4_Guest_lecture_by__.md  index 82ac722..4831996 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 fat old men doing mathematics in London, were the active players in the Industrial Revolution.