This heavy book contains instruction on improving critical thinking and reasoning, but entwined with the words is a powerful magical effect that grants a permanent +3 inherent bonus to Intelligence. This effect will not stack with other inherent bonuses to Intelligence (like those from other tomes) but will replace them if greater. Hover over your stats in your character sheet to see if you already have an inherent bonus to a stat.

The maximum applied bonus to an ability score from Inherent bonuses is capped by character level, but you can have potential bonuses higher than that. At level one and two, you cannot benefit from any Inherent ability score bonuses. Applied bonuses to your character are unlocked with higher character levels:

Level 1: +2
Level 3: +3
Level 7: +4
Level 11: +5
Level 15: +6
Level 19: +7
Level 22: +8 and higher