Hidden Factors in Economic History

 I'm intrigued by the idea that some hidden factors account for economic gains:

• The invention of eyeglasses. That must have significantly improved the capabilities of a segment of the population 
• The change from women as housewives to women as teachers to women as professionals.  Those changes raised the average intelligence of the (paid) workface, while lowering the average for the teaching profession.
• The opening of "virgin land"--meaning the exploitation of fertility accumulated over years
• The invention of the container ship.  (Good book on that.)

[Updated 1: The invention of writing of course was important, as were the inventions of libraries, and public libraries, and lenses which were prerequisite for glasses and then Ben Franklin's bifocals.

Updated 2:  The adoption of uniform time zones in the 1880s]