Tomes of Understanding are magical tomes that increase the character ability of Wisdom by one point and are consumed when the point is added. One tome can be found during the quest to rid yourself of the poisoning from Marek. The second tome can be found in the Underground passages of Candlekeep, and the third tome can be found on 3rd floor of Durlag's Tower. This item appears in Baldur's Gate and Baldur's Gate: Enhanced Edition.
A typical Tome of Understanding contains a sober, if dry analysis of legal battles, historic events, government policies, philosophical treatises and theories of magic and metaphysics. While rarely interesting to anyone outside of their already well-educated niche market, it is said that some such tomes have even added a single point to the Wisdom of certain half-ogres. Such marvels, however are the product of a potent magic placed upon the tome as it is being written. Unfortunately, the same magic causes the tome to disappear after a single use.