If the library would allow Theo to expand his knowledge over the narrow selection of fields he knew to be important, then the central marketplace of the academy was the best place for him to expand said selection.
It was a place where people from all sorts of departments and walks of life would come in and trade away their wares to obtain money and credits necessary for them to buy stuff they needed and only others could provide.
In a certain way, the central marketplace was a snapshot of what any economy would look like, centralizing most of the high-end and high-volume trade that went through the academy.
Those who just finished their missions, during which they defeated powerful monsters or found rare herbs, would come to the marketplace to either sell those things in bulk in one of the few leading wholesale companies or put them up to auction in one of the seven auction houses, each dealing with a different kind of merchandise.
