Tractate Shekalim teaches: On the first of the month of Adar, the Beit Din reminds people to give the half-shekel and to abstain from cross-breeding plants (Kilayim).  These two laws represent competing values. Whereas the half-shekel was a universal obligation that applied to everyone, the prohibition of Kilayim strives to maintain the differences that are present in nature. Adar is the last month on the Jewish calendar. When it arrives we must evaluate how well we balance these competing values that are both sacred and necessary.