This page of our guide to Psychonauts 2 lists the Nuggets of Wisdom available in Cassie's Collection.
You can find four Nuggets of Wisdom in this level.
1 Nuggets of Wisdom
Location: Librarian's Desk.
To get to this secret, you have to stop the platforms that are constantly moving. Then, from the shelf with the documents, jump to a small pit. The Nuggets of Wisdom is there.
2 Nuggets of Wisdom
Location: Exhibit C.
To get to this secret, you just have to go out of the book in Exhibit C.
3 Nuggets of Wisdom
Location: Deep Inside Teacher's Domain.
To get to this secret, you have to jump through thoughts to a small hole in the wall.
4 Nuggets of Wisdom
Location Exhibit B.
The last Nuggets of Wisdom in this location you will find on the books. All you have to do is jump to the spot shown in the picture above and then climb onto the red cover.