This discourse was taught by the Rebbe for Shabbat Sedra Korach in 1967.  Korach wanted to cause a division in the Jewish people. The discourse explores the she source of all such 'divisions' and conflicts,  going back to the beginning of Creation when the firmament was created on the second day, dividing between the lower waters and the upper waters.  Division is an integral part of our world, but the goal is unity.