Inner Reservoir

The 'inner reservoir' refers to the pool of mana present within all living beings. It is possible for an individual to tap into this mana pool, which allows for many magical feats. Such feats include channeling significant quantities of mana in order to fuel powerful spells, as opposed to simply channeling from the limited mana in the immediate area around oneself.
With proper training, it is possible to delve deeper into one's inner reservoir and access more of the latent mana from within. No documented individual has ever discovered a "bottom" to their inner reservoir, leading many arcanists  to speculate that there simply is no limit. This, however, has yet to be proven.