I remember I wrote a creation story once. There were three types of magical essence :
'Pure' Essence : This was the sort of essence gods used to make other gods and galaxies and somesuch. No mage has been able to harness this.
'Greater' Essence : This sort of stuff was used by the gods to make the first races and shape worlds, etc. This is the stuff powerful mages, or mages worth the title use.
'Lesser' Essence : This was the inherent energy inherited by the lesser races as they grew further from their origins of god. All humans have this and can, with effort, use it. Parlour magicians and amateur magi use this to fuel their magic.
There was also different types of magic : Willpower magic, which relied upon willpower and conjured typical magical effects : bolts of lightning, fireballs, storms, cold snaps, etc. Meta-Philosophy magic, that used knowledge and small puffs of magic here and there to make things happen, like create a wave made of wood. (Think of Full Metal Alchemist.) There was also Conventional Magic, which was somewhere between the two, and an 'Ultimate' magic, that was basically the mastery of the first two schools to the point that you could use them to their maximum potential.