For the secular in Israel, it is similar to Arbor Day in the United States. Historically, it has been celebrated for over 1000 years and marks the time of year for calculating when the agricultural cycle began or ended for the purpose of biblical tithes. It is considered a "new year" celebration and is one of 4 new year celebrations in the Jewish Calendar. In the sixteenth century, the mystics of Safed associated the tree of the fruit-year with the S’phirot or Kabalistic Tree of Life. Thus, Tu B’Shvat is the day the Tree of Life renews the flow of life to the universe.