In earlier or simplified systems, sometimes Intelligence is the only statistic that determines magical aptitude for both Black Magic and White Magic. It is often also associated with the character's ability to reason and sometimes as a measure of their Faith.
The Mind skill affects the potency of healing magic. For this reason, it is the primary attribute of class Conjurer and jobs Scholars and White Mages. The Cleric Stance ability lets them switch their Mind and Intelligence stats, allowing them go on the offensive as needed.