In Parashat Ki Tavo, we find a list of terrible "curses" to be brought upon the Jewish people if they don't keep the laws of Torah and serve G‑d "in happiness." But why should such a terrible punishment be meted out to the Jewish people just for not being happy?

To understand the answer, we must first understand how mitzvah fulfillment works.

...the 248 positive commandments correspond to the 248 limbs and organs of the body.

The Sages of the Kabbalah and the Chassidic masters explain that the 248 positive commandments correspond to the 248 limbs and organs of the body. When we work to fulfill these commandments, we attach each section of the body to its spiritual counterpart above and bring down the corresponding spiritual influx to enliven ourselves and the universe. That is why Moses pleaded with G‑d to let him enter the land of Israel. Only in Israel can one fulfill all 248 mitzvahs and therefore be spiritually complete.

However, not everyone is able to fulfill all of the commandments. Most obviously, we cannot bring sacrifices to G‑d, since today we don't have the holy Temple. If so, how are any of us to attain the spiritual completion associated with performance of all 248 of the positive commandments?

Shem miShmuel says that since all Jews are guarantors for each other, and we come from one spiritual source, the commandments we fulfill as individuals influence all Jews. This is true not only among contemporaries, but across the generational divide as well. Jewish souls – taken collectively from the beginning of time – form a spiritual whole in which each part (or soul) interacts with every other. The mitzvah of fulfillment of one Jew has an influence on every other Jew and makes up for what another may not be able to do. And therefore, everyone who lives without the Temple in Jerusalem is "covered" by those who brought sacrifices in previous generations. Our own individual fulfillment is brought about by the collective fulfillment of mitzvahs of all the Jews together.

But, says Shem miShmuel, there's a hitch. All of the above is true when we consciously identify with, and include ourselves in, the collective whole of the Jewish people. And that can only happen if we are happy.

Mitzvahs are meant to be accompanied by happiness.

Mitzvahs are meant to be accompanied by happiness. If we perform them dispassionately, doing them coldly and without feeling, we may be fulfilling the will of the One Above, but we fail to attach ourselves to the collective identity that unites all Jews together.

However, when we do mitzvahs happily, we elevate our soul and make it part of the spiritual community of Jews above, where all souls are bound together in bonds of love and friendship. Only when we are happy can our soul be united with all other souls in a state of happiness.

On such occasions, we also bring down for ourselves "credit" for fulfillment of mitzvahs which we were actually unable to fulfill (either because we're in the "wrong" generation of the "wrong" place). When we join forces with the rest of the Jewish souls in happiness, the souls which were able to fulfill those mitzvahs in their generations are able to pass on the "credit" to us as well.

However, when we are unhappy we don't connect Above, and therefore we cannot bring down any extra "credit." And not only that – because we are now incomplete in our fulfillment of mitzvahs, we leave ourselves open to the curses mentioned in Parashat Ki Tavo, "since you didn't serve the One Above in happiness."

Shem miShmuel concludes by saying that understanding the above is essential as preparation for Rosh Hashanah. It's not enough to do teshuva if we subsequently come before the King without completely fulfilling all of the mitzvahs. Therefore, we need to reinforce our communal love and unity as we approach Rosh Hashanah and Yom Kippur. We need to work not only on asking forgiveness for the past, but also to take upon ourselves the intention of happily fulfilling all the mitzvahs we can, so that we will unite with the rest of the Jewish people, not only of our own generation but those of past generations as well!

[From "Inner Lights from Jerusalem". Translated and presented by Rabbi David Sterne.]