Harry Potter's World of Magic Theme Park School Houses

an excerpt from a site that also has a Sorting Hat. This explains the philosphy....
The Philosophy of Four
The historical significance of the number four
. One School = Four Houses. But why only four? There is one house for each of the founders of Hogwarts, but there is more to it than that.
Four has long been considered an auspicious and magical number signifying stability, harmony, and balance.
A year has four seasons. A square has four sides and four right angles. A measure in common time has four beats. A deck of cards has four suits.
Four has been used in philosophy and religion for centuries. Ancient Greek philosophers and medieval alchemists adopted Empedocles' four elements: fire, water, earth, and air. Native Americans oriented themselves according to the four directions: north, south, east, and west.