Throughout the ages, what we now know as civilization has 
come about through only one means, knowledge. Knowledge comes in
many forms, and in many different fields. Many of the most powerful
figures in the realms today, have not fought for their positions as
much as they have gained them through knowledge. Magic, from its 
inception, has been an unparalleled tool in gaining knowledge. 
Any magical spell that allows either the target or the caster to
know something previously unknown, is part of this family of spells.
The only real prerequisit to cast this type of spell, is the 
thirst for knowledge.