oldstarnewshine:

the x and y axes being your personal motivations (self/others) and your ultimate goals (humans/humanity)

• gryffindor: others/humanity
• hufflepuff: others/humans
• ravenclaw: self/humanity
• slytherin: self/humans

the harry potter series, and pretty obviously jkr, values bravery over all other virtues, so the houses that value humanity (our place as a species in a greater cosmic universe) are generally portrayed as more virtuous than the houses that value humans (immediate happiness in the here and now).  our heroes are gryffindors and we get a lot of supporting ravenclaws, but hufflepuffs are generally seen as sort of frumpy and pathetic and slytherins are almost uniformly evil or odious. 

where the series falls flat in this way of sorting people is that there is a z axis to consider, of how you enact your x and y axes:  the idea of a “good slytherin” (like narcissa) or an “evil gryffindor” (like peter), because ultimately caring about you and yours and being concerned with immediate happiness do not come bundled with being a fundamentally bad person in the same way that ultimately caring about the good of others and being concerned with the cause do not come bundled with being a fundamentally good person; as well as that often people evolve and ultimate set-in-stone sorting at age eleven is ridiculous.