Near the end of this book is this awesome idea called the Year of Jubilee. Yahweh of Israel had commanded the Israelites to regularly rest from work. He commanded them to rest from work on the seventh day of the week, to rest the fields every seventh year, and then after forty-nine years, the fiftieth year was the Year of Jubilee. In chapter twenty-five Moses explains how it is supposed to work. This year of rest and celebration was also a time when slaves were set free, when land was returned to orignal owners, when debts were canceled.
Slavery was part of the economy, if you owed debts, you could sell yourself or family to a landowner or some other owner, and there purchase of you would cancel the debt. Slavery was a way for people to be taken care of, rather then left to their own fate in a rough and harsh land. Jubilee was about setting people free. God had sent them free from slavery in Egypt, and now he was instituting a similar idea for them twice a century.
What a unique festival with huge implications!