deletions | additions       diff --git a/Lecture_4_Guest_lecture_by__.md b/Lecture_4_Guest_lecture_by__.md  index 1b3f772..dfa32f7 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 represented  "human capital" (not fat old men doing mathematics/accounting in London), were the active players in the Industrial Revolution.