The book "An Epidemic of Absence" documents the hygiene theory mentioned in his piece. There is a review of that book here [1] [1] https://www.nytimes.com/201

The book "An Epidemic of Absence" documents the hygiene theory mentioned in his piece. There is a review of that book here [1] [1] https://www.nytimes.com/2012/09/11/science/an-epidemic-of-absence-review-seeing-hygiene-as-driver-of-disease.html https://www.nytimes.com/2012/09/11/science/an-epidemic-of-ab...