The Alter Rebbe begins by explaining that mitzvos were given to us through a process of התלבשות במדת גבורה וצמצום ההארה—being enclothed in the attribute of Gevurah and a contraction of the Divine light. In other words, the infinite light of the Ein Sof cannot come down into this world in its full intensity; it needs to be limited and measured so that we, as finite beings, can receive it.

This is why, he says, most mitzvos have a specific, limited measurement. The Torah gives us exact requirements for how each mitzvah is to be performed. For example, the אורך הציצית—the length of the tzitzis—must be twelve gudalin. The תפילין—tefillin—must be two by two fingerbreadths, and they must be specifically square. The לולב—lulav—must be four tefachim. The סוכה—sukkah—must be seven tefachim. The שופר—shofar—must be at least one tefach. The מקוה—mikvah—must contain forty se'ah of water.

All of these details show that the mitzvos are not just spiritual ideas, but are brought down into the world in a way that is measured and defined. This is a direct result of the Divine light being contracted through Gevurah, so that the mitzvos can exist within the limitations of our physical world.

The same principle applies to korbanos—the offerings brought in the Beis HaMikdash. Each type of korban has a שיעור מצומצם—a specific, limited measurement, not only in quantity but also in time and age.

For example, a keves—a sheep—must be within its first year. An ayil—a ram—must be within its second year. The same applies to parim—bulls—and other offerings; each has its own defined age and requirements.

This again demonstrates that even in the realm of korbanos, which are spiritual acts of drawing close to Hashem, the Torah insists on precise, measured limitations. The Divine light is contracted and expressed through these specific boundaries, making it possible for us to fulfill these mitzvos in the physical world.

The Alter Rebbe continues that this idea of measured mitzvos applies even to מעשה הצדקה וגמ"ח בממונו—the act of tzedakah and acts of kindness with one's money. Even though tzedakah is considered one of the pillars upon which the world stands, as the verse says, עולם חסד יבנה—the world is built on kindness—even so, there is a שיעור קצוב—a set, defined amount for how much one should give.

For someone who wants to do the mitzvah in the most ideal way, the choicest way is to give a fifth (20%) of one's income. For the average person, the standard is to give a tenth (10%), which is called ma'aser.

This shows that even in the area of tzedakah, which is so fundamental that the world depends on it, the Torah still sets clear boundaries and measurements. The mitzvah is not left open-ended, but is brought down into the world in a way that is defined and limited, just like all other mitzvos.

This measured kindness is what the Alter Rebbe calls חסד עולם—the kindness of the world. He explains that this refers to the verse חסד אל כל היום—the kindness of G‑d all day—which is enclothed within the upper and lower worlds.

How is this kindness drawn down? It happens ע"י אתערותא דלתתא—through an arousal from below, specifically through the mitzvah of tzedakah and acts of kindness that people do with one another. When we perform these acts, we bring down this Divine kindness into the world, but it comes in a measured, limited way, appropriate for the world as it exists.

The reason for all these limitations is because העולם הוא בבחי' גבול ומדה—the world is, by its very nature, defined by boundaries and measurements. The Alter Rebbe illustrates this with examples: from the earth to the sky is a distance of five hundred years, and the same measurement applies from one sky to the next, through all seven heavens. Even the existence of the world itself is limited to six thousand years.

Because the world is inherently limited, the mitzvos of tzedakah and chesed in the Torah are also given with specific measurements and boundaries, just like all other mitzvos. The Torah brings the infinite light of Hashem into the world in a way that fits the world's limitations, so that we can fulfill these mitzvos in a practical, tangible way.