High Sorcery is the magic of wizards, given to them by the moon gods – Solinari, Lunitari, and Nuitari. Whereas clerics have to pray to their deities in order to access spells, High Sorcery is always available to those wizards who know the arcane secrets of activating the magic. Whether an individual is aligned with the Wizards of High Sorcery or a renegade, they can access this power. Those who pursue the path of High Sorcery study for a lifetime before mastering the power.
The gods of magic brought this power to the world after seeing the destructive magical storm caused by Wild Sorcery in the early history of Krynn. They recruited the first Wizards of High Sorcery, and began training them in a way to access the power without being a danger to the world. It is for this reason that the orders have instituted the Test of High Sorcery.
Once a wizard passes the Test (if they survive), they are then aligned with one of the moons, based on their moral alignment. White Robes revere Solinari, Red Robes revere Lunitari, and Black Robes revere Nuitari. The moon a wizard is aligned with will affect their magic as it waxes and wanes, much as the moons affect the tides.