From the book intro:
"There are many schools of magic. Some, such as Evocation, are combat oriented and the province of wizards who hurl deadly fire at their foes and wreathe the battlefield with lightning. Others, such as Transmutation, are the domain of those seeking to explore the many forms of reality and how they can be bent and reshaped. Still others are much subtler; the school of Abjuration, for example, is a generally passive art that seeks to protect both body and soul.
Divination is an art considered weak and secondary in the eyes of many who should know better. A diviner is likely to always be considered a support character at best, an annoying, second-rate wizard with nothing useful to contribute at worst. For those who take divination seriously, however, the scope of their potential is immeasurable. After all, who is truly more powerful - the wizard with the fireball or the diviner who tells him when and where to cast it?"