In his Sefer Hamidot, Rebbe Nachman of Breslov writes: “When you suddenly feel that joy has entered your heart, it is because a tzaddik (righteous person) has been born.” When a tzaddik is born, joy descends to the world. God is happy, the heavenly angels are happy, and everyone from the soul-root of that tzaddik gets a taste of the great joy generated by his birth. Suddenly, you are happy because your soul senses that a new light has been born in the world—a tzadik who will hasten the redemption with his unique service of God.
When the tzaddik, Rabbi Levi Yitzchak of Berditchev, was born, the Ba’al Shem Tov made a joyous feast with his disciples. When Rabbi Shneur Zalman of Liadi—the Alter Rebbe of Chabad—was born, the Ba’al Shem Tov told his disciples that they should rejoice, for “the pride (genius) of Jacob” (Psalms 47:5) has been born.
The Chassidic interpretation of the Divine directive to “be fruitful and multiply” is that every Jew must make another Jew by bringing him close to the ways of God, the Torah, and the commandments. All Jews are righteous, so everyone can give birth to a tzaddik! Every Jew who comes closer to God is a newborn tzaddik, and he increases joy in the world.
The last words we heard from the Lubavitcher Rebbe were, “…With an abundance of music and song.” Even when the Rebbe was struggling with his health, he instructed his followers to be happy and raise their voices in song. He impressed upon them that thanks to their joy and happiness, all harsh judgments would be annulled and sweetened, and Mashiach would come.
As a rule, we should “practice what we preach” before trying to influence others. In our case, this means being happy ourselves and only then making others happy. Appropriately, the letters of “Mashiach” (מָשִׁיחַ) permute to read “he will be happy” (יִשְׂמַח) and he also “makes [others] happy” (יְשָׂמַח).
However, it can sometimes be hard to feel happy. If that is the case, we can begin by making others happy—until we, ourselves, are infected by their joy. The sages teach that someone who inspires someone else to do a good deed is more praiseworthy than the person who does it (Bava Batra 9a). In the same vein, someone who makes others happy is more admirable than the person who becomes happy. The joy of the happy person then rebounds back to the person who made him happy, and he becomes a conduit for even more joy.
Making others happy is an act described as illuminating “direct light” (אוֹר יָשָׁר) while the joy that reflects back to the person who made others happy is termed “returning light” or “reflected light” (אוֹר חוֹזֵר). Reflected light penetrates the origin of joy and thus has an advantage over direct light. The joy returns to the person who aroused it, enabling him to bring joy to others, forming a never-ending cycle of rejoicing and giving joy.