He spends a lot of time wondering what it means to be human, and if things like jealousy and rage and stupidity makes you less human, or if they are just as much a part of humanity as the rest. He wonders what it would take to lose your humanity, and if it is as easy as snapping into a rage or committing a sin, or if it's much harder, if it takes years of mental preparation and practice, or if some great machine can extract it, or some lengthy procedure can just turn it off.
And he wonders if he might one day lose his humanity, and what that would mean for his crew, and his species, and his home.