In memory of Rabbi Levi Yitzchok ben R' Zalman Yuda Deitsch OBM
The concept of simcha (joy) shares a connection to the Future Redemption. For it is in the Era of the Redemption that we will experience the consummate level of simcha. At that time, all undesirable influences will be negated as reflected in the verse, (Isaiah 25:8) "And G-d will wipe away tears from every face." Indeed, all the negative influences will be transformed into good.
(The Lubavitcher Rebbe, 14 Elul, 1988)