craft the book (for any resource/craft)
fill book while crafting/gathering
give book to the slave (NPC gives 10-50% resources from book after 24hrs)
upgrade slave, upgrade book
buy books, sell books
(spend money instead time for crafts and farming)
(spend resources and time for upgrade slaves not alt chars)
(get additional resources/money from books with no additional time spend)
P.S. "Albion Online" system