But while we know a great deal more about sleep now than when Galen was around, we still haven't understood why it is that sleep, of all of our activities, has this incredible restorative function for the mind.
Ali unatoč tome što danas znamo mnogo više o spavanju negoli u Galenovo vrijeme, još uvijek nismo otkrili  zašto baš spavanje, od svih naših aktivnosti,  ima ovakvu nevjerojatnu funkciju obnavljanja uma.