“…A constant fire shall burn upon the altar; it shall not be extinguished…” – Vayikra 6:6

אֵשׁ תָּמִיד תּוּקַד עַל הַמִּזְבֵּחַ לֹא תִכְבֶּה – ויקרא ו, ו

The Torah commands us to constantly burn a fire on the Outer Mizbei’ach, the altar that stood in the courtyard of the Temple, and to never extinguish it. Moreover, as taught in the Talmud Yerushalmi (Yoma 4:6), the Torah’s emphasis on this fire’s constancy comes to teach us that this fire must be continuously maintained, even if the kohanim responsible for it are in a state of ritual impurity.

This detail in the service in the Mishkan and Beis Hamikdash is equally vital in the spiritual Mishkan that we each must create within ourselves.

The altar represents the heart of man, and the fire on the Outer Mizbei’ach represents a conscious and heated passion for G-dliness. The Torah’s demand that even when the kohanim are in a state of impurity they must still maintain the fire on the altar addresses the person who feels impure and defiled—distant from anything holy. Notwithstanding his undesirable spiritual state, he must never allow the G-dly fire that burns in his soul to be extinguished. He, too, is commanded to continuously fan the natural flames of excitement toward anything G-dly that burn in his heart – as they do in the heart of every Jew.

By keeping that fire alive, he will ultimately purge himself of impurity as well. As the Maggid of Mezeritch interpreted this verse homiletically: “When the fire on the Altar is constant, everything “not” (i.e., negative) shall be extinguished.”

—Likkutei Sichos vol. 1, p. 217