Chai Elul -- birthday of the Baal Shem Tov and the Alter Rebbe (Baal Hatanya and Shulchan Orech)

[...] the neshamoh — soul — of the Alter Rebbe, one of the celebrants of today’s birthday, was a neshamoh chadoshoh — a new soul. It had never before descended to this world! And now the time had come for such novel things to be achieved, that a new soul was needed. And the soul of the Alter Rebbe was summoned to give new meaning to the concept of a dwelling place for G-d.

From all this we can understand the reason for great celebration on this day. For by virtue of their greater powers than the ordinary man, the two luminaries were able to accomplish so much more by their birth.

As stated above, the Baal Shem Tov and the Alter Rebbe, whose birthday it is today, were called the “Two Great Luminaries.” When Moshe Rabbeinu was born we are told in the Torah (Exodus 2:2): “she saw him that he was goodly.” On which the Talmud comments (Sotah 12a): “When he was born the entire house was filled with light.” This means that as soon as Moshe was born, he had an effect on the world — the house was filled with light.

What is light? It does not change the form or substance of anything. It merely shows where or what something is. When it is dark in the room, one sees nothing more than vague outlines. And one certainly cannot differentiate between colors. Light changes this and comes to reveal what is present and which form it takes.

A Jew, however, must not be satisfied with merely revealing the truth. It is demanded of us that we actually become “partners with G-d in the creation.” Not like a partner who only has an equal share in the business, but like a partner who had the same hand in building the business as his counterpart! Because of this, he feels free to make improvements and innovations as he sees fit. This is the nature of our partnership with G-d; He has given us the power to bring about profound changes in the creation by our actions and good deeds.

This is why the Baal Shem Tov and the Alter Rebbe are called the two luminaries. A luminary is the source of the light and not merely that intangible phenomenon which reveals what is already there. And this is why they are called the two great luminaries’ ‘ since the changes that they were responsible for were great ones, lasting throughout subsequent generations. Their deeds shone brightly and their influence was everlasting. When they taught their students they made sure that not only would their teaching never be forgotten but that their students would in turn teach others.

Lubavitcher Rebbe, sicha of 18th Day of Elul, 5742