Upon reading the question posed here I wondered about what kind of slavery was being denoted and why one would seek to write a book on slavery instead of a book on freedom. Just like the safest prison involves one where the inmates believe they are free while incarcerated and incarcerated while free and thus willfully stay incarcerated, there exists a similar effect related to the question of productivity under slavery where the slaves / the workers are the most productive when they believe they are doing the work as willful workers instead of realizing they been enslaved. Now I realize some may be writing a book on slavery/freedom while actually writing a book on freedom/slavery as a way to get through to them under the influences of certain ideologies to consider better ways... though I would wonder if that was the case here and how some seek a solution to a problem instead of seeking to do what better be done as it better be done via handling the situations accordingly (hint a solution implicates a problem and thus creates the problem to solve ... whilst handling the situations accordingly implicates handling the situations accordingly )