John Stuart Mill,
Principles of Political Economy
“ It is a matter of common experience that a change of occupation will often afford relief where complete repose would otherwise be necessary, and that a person can work many more hours without fatigue at a succession of occupations, than if confined during the whole time to one.116 Different occupations employ different muscles, or different energies of the mind, some of which rest and are refreshed while [pg 106] others work. ”
