What does Faith learn about the Mendacity Tree while reading through her father's notebook?

In reading her father's notebook, she learns that her father encountered a man named Hector Winterbourne, who told him about the Mendacity Tree, which thrived in the darkness and bore fruit only when someone fed it lies. The person had to tell the lie to the tree, then pass off the lie among other people. The tree produced bigger fruit in response to more important lies that were widely believed. The person who eats the fruit is “granted knowledge of a most secret sort, and on a matter close to their heart” (153).