The central theme of this week's Torah portion is that of the Sabbatical year, known as "Shemitta". Every seven years the land of Israel must lay dormant -- no agricultural work may be performed on the land. Right to this very day, the rules of Shemitta are observed and many Jewish farmers do not plant, prune, or even harvest. After seven Shemitta years -fifty years in total - was the "Yovel" - the Jubilee year.