There is a direct theme that seems to be apparent in the Old Testament, and that is man sins and bad things happen.  People have the choice to repent and this was a job for most of the minor prophets.  The minor prophets were sent by God to call for repentance from the people.  They were called the minor prophets because they wrote small books.  Not because of their importance, but as a result of their size.  If you would like to read of Revelation  press here!