The kanji 本 (book, origin) is derived from 木 (tree) with an extra horizontal stroke at the bottom. This stroke highlights the roots, indicating the 'origin' or 'base' of the tree. From the idea of the 'root' or 'source', it extended to mean 'book' (as a primary source of knowledge, or paper coming from wood) and 'main' or 'true'.
'Hon' — A HONEST book reveals its true ORIGINS, just like this kanji shows the root of a tree.