You shall observe My statutes and My ordinances, which a man shall do and live in them. I am HASHEM. (Vayikra 18:5)

Why is this Holy advice sandwiched in between an admonition not to follow the wicked practices of the Egyptian or Canaanite Culture and the Commandment to not become involved in uglies of uglies of incestuous relationships? Why is this smack in the middle?

What does it mean that a person will “live in them”? How does one live in a statute or an ordinance of HASHEM? What kind of place is that to live in? How big is it and where is it? How does one live in it? What does this mean? What kind of promise is this?

Quoting the Zohar, Reb Chaim Volozhin writes the following in a footnote in Nefesh HaChaim: As soon as someone has it in mind to perform a Mitzvah something of a “trace” (i.e., an impression) of that Mitzvah is implanted in its celestial source above — even before the person actually performs it.

And that enables a “surrounding light” to shine down upon him, and for a degree of holiness to encompass him. That holiness and the encompassing lights then enable that person to “attach himself onto G-d”, if one could say as much, in his lifetime.

The “encompassing light” then helps him to actually fulfill the Mitzvah, which then strengthens that light. And that then gives him the wherewithal to fulfill yet another Mitzvot given that he’s “literally sitting in the Garden of Eden” You can actually sense the holiness you’re surrounded by at that time if you concentrate, and can thus grow in your soul. This is what it means “to live in them” to actually live in them.

The opposite is true, too, though. For when you sin —you draw a spirit of impurity down upon yourself, become surrounded by an impure spirit, and the very “air of Gehenom surrounds you” even though you’re alive.

Reb Chaim is explaining what the spiritual dynamics are when performing a Mitzvah and why it is appropriate for us to declare before doing a Mitzvah- “Asher Kidishanu B’Mitzvosav” – “That we are made Holy with His Mitzvos.”

We are becoming Holy beings. We are living in the Holy environs created by the Mitzvah which attaches us to HASHEM. We are living in the Mitzvah, in Gan Eden, while in this world.
That Mitzvah creates an inertia and leads us to another Mitzvah and further momentum is generated from that Mitzvah. So, it is written in Pirke Avos, “Run to pursue a minor Mitzvah, and flee from a transgression. For a Mitzvah brings another mitzvah, and a transgression brings another transgression. For the reward of a Mitzvah is a Mitzvah, and the reward of transgression is transgression. (Avos 4:20)

The reward of a Mitzvah is that it generates another Mitzvah and the Mitzvah itself is the reward. Being attached to the Holiness of HASHEM is the greatest reward and delight that nothing in this world can compete with. A Jew who performs Mitzvos is becoming holier and holier.

Rabbi Avigdor Miller explained that an older Jew is holier than a younger Jew because he has spent more time soaking (like a pickle) and soaking in the Holy environs of Tzistis, and Tefillin, and Shabbos, and Sukkos, and Torah learning etc. He is spiritually cured by living in Mitzvos during his lifetime.

Rashi says about the expression “living in them”, and live in them: “in the World-To-Come…Olam Haba…” There the full flavor of what was accomplished in this world will be revealed. It’s called Olam Haba, literally “the world to come” because it comes from this world. It is an extension of and a result of what we do in this world. There we are bathing in the ultimate light of Mitzvos. The reward of the Mitzvah there is clearly the Mitzvah itself. It could all be very different if one is seduced by his lower urges. He can be led to the darkest places. Better to acquire a taste for Mitzvos and to live in them.