SRD:Tome of Clear Thought

Tome of Clear Thought: This heavy book contains instruction on improving memory and logic, but entwined within the words is a powerful magical effect. If anyone reads this book, which takes a total of 48 hours over a minimum of six days, she gains an inherent bonus of from +1 to +5 (depending on the type of tome) to her Intelligence score. Once the book is read, the magic disappears from the pages and it becomes a normal book. Because the tome of clear thought provides an inherent bonus, the reader will earn extra skill points when she attains a new level.

Strong evocation (if miracle is used); CL 17th; Craft Wondrous Item, miracle or wish; Price 27,500 gp (+1), 55,000 gp (+2), 82,500 gp (+3), 110,000 gp (+4), 137,500 gp (+5); Cost 1,250 gp + 5,100 XP (+1), 2,500 gp + 10,200 XP (+2), 3,750 gp + 15,300 XP (+3), 5,000 gp + 20,400 XP (+4), 6,250 gp + 25,500 XP (+5); Weight 5 lb.