If you're a single-celled creature, you basically need to do everything on your own

To be a body is for each part to do things for the others. For example: every cell in our body requires oxygen, but it is the mouth and lungs that inhale it and process it. Similarly, every part of the body needs or wants to eat, drink, think, talk, sing, walk, dance, toss a ball, plant a garden and watch a sunset. Certain tissues, organs and limbs assume the task and do it for everyone else.

When a mouth talks, it's not a mouth talking—the entire body is talking via the mouth. The same thing happens A body is more than a physical object. It is a spiritual idea when the brain thinks, the stomach digests, or the big toe of the left foot tests the bathtub temperature.

A body is more than a physical object. It is a spiritual idea: the concept that an action by one of the collective parts is, in essence, an action of the whole.

Imagine a person trapped under a collapsed building. The search and rescue team has located him, but it will take them many hours to dig him out. But there is a small fissure in the rubble—just large enough to allow him to extend his hand to them. Because they are in contact with this single limb, they can monitor his vital signs, offer comfort and encouragement, and even infuse him with the needed fluids, nutrients and medication to sustain him until he can be completely freed.

All of Israel is a single body Back in the days of communist rule in Russia, the Rebbe employed this metaphor to describe the state of Soviet Jewry. The study of Torah and the observance of the mitzvot are our very lifeblood; without them we cannot survive as a people. Yet for three generations, millions of Jews could not conduct a Passover seder, light a Shabbat candle, read a verse of Torah or affix a mezuzah on their door; they lived trapped under conditions that prevented them direct access to the food and oxygen of the Jewish soul. Would these portions of our people atrophy and die, G‑d forbid?

But all of Israel is a single body, the Rebbe maintained. When a Jew in New York does a mitzvah, the entire body of Israel is performing this mitzvah; when a Jew in Tel Aviv says a prayer, the entire body of Israel prays through her. We are the limb extending from the rubble; we are keeping them alive.

As much as we sustain them, they sustain us The Rebbe also said this: It works the other way around as well. We are fortunate in that we need not make any great sacrifices to be Jewish; we do not face the daily tests of faith and the constant challenges to our very identity that the Jews living under Soviet rule do. We are free to express and actualize our Jewishness without hindrance. But freedom and prosperity can be no less a threat to Jewish survival than hardship and persecution; we face the pitfalls of complacency and indifference. In this sense, we are the body trapped beneath the rubble and they are the extended hand... As much as we sustain them, they sustain us.

Today, we once again face a situation in which a significant part of our people are living under hardship and threat. Our brethren in the Land of Israel are surrounded by enemies who rain rockets of death and destruction on their train stations and apartment buildings and blow themselves up in their streets and shopping malls; while a largely indifferent world intervenes only to attempt to restrain Israel's efforts to defend itself.

Over the years, whenever the Jews in Israel faced similar threats from their enemies, the Rebbe would call upon us to increase our acts of goodness and holiness. A mitzvah on our part, the Rebbe would urge, will bring protection and safety to our brethren in the Holy Land. (see presentation).

On the most basic level, we might understand this as a tit-for-tat dynamic: we send a prayer or mitzvah up to G‑d, and in return, G‑d sends down His blessing and protection to the Jews in Israel.

On a deeper level, it's not a matter of "us" doing something for "them." If we truly regard ourselves as a single body, then every positive and G‑dly deed we do increases the spiritual vitality of the entire body of Israel. Every mitzvah we do infuses our collective being with the strength and fortitude to emerge victorious in all our battles and achieve security and tranquility in our land.