The fire of Torah consumes the yetzer hara

בפסוק היא העולה על מוקדה במדרש עולה בא על הרהור הלב וכן בזוה"ק מחשבה רעה העולה בעי לאוקדא לה בנורא כו'.

On the verse "It is the olah-offering on its pyre (mokdah)" (Vayikra 6:2): in the Midrash, the olah comes [as atonement] for the sinful thoughts of the heart (hirhur ha'lev); and likewise in the Zohar HaKadosh, an evil thought that "rises up" — one needs to burn it in fire.

The Sefas Emes opens with the teaching that the olah atones for improper thoughts, and the Zohar's image of "burning" a bad thought that arises within a person.

וכתיב על מוקדה משמע שיש לכל מחשבה רעה מיוחד לה אש של מצוה מיוחדת לאתוקדא תמן.

And it is written "al mokdah" (on its pyre), implying that for every evil thought there is a particular "fire of a mitzvah" designated for it, to be burned up there.

Reading "on its pyre" precisely, every bad thought has its own corresponding mitzvah-fire in which it is meant to be consumed.

ובאמת מצד זה יש לה קיום.

And in truth, from this very fact it has an existence (kiyum).

The evil thought's very reason for arising is so that it can be burned in its matching mitzvah-fire — that purpose is what grants it existence in the first place.

וזה עצמו פי' הכתוב היא העולה על מוקדה שמצד זה המוקד היא עולית במחשבת האדם.

And this itself is the explanation of the verse "It is the olah on its pyre": that on account of this "pyre" it "rises up" (olah) in the thought of a person.

Playing on olah ("rises"/"ascends"), the bad thought "comes up" in a person's mind precisely because of the fire destined to consume it — its ascent serves its eventual burning.

ובזוה"ק ואתחנן על פסוק בכל לבבך בשני יצריך ואיך אפשר לעבוד למקום ביצה"ר.

And in the Zohar HaKadosh, Parashas Vaeschanan, on the verse "with all your heart (levavcha)" — "with both your inclinations" — and how is it possible to serve Hashem with the yetzer hara?

Chazal read the doubled "levavcha" as serving Hashem with both inclinations, the good and the bad; the Zohar asks how the yetzer hara could possibly be used to serve Hashem.

ומפרש כמו ברזל שע"י האש מתרכך כמו כן היצה"ר אם ברזל הוא כו'.

And it explains: just as iron is softened by means of fire, so too the yetzer hara — "if it is [hard as] iron [the fire of Torah will crack it]."

The answer: fire softens even iron. The "fire" of Torah and mitzvos can melt down and transform the hard yetzer hara, harnessing it for avodah.

וז"ש אש תמיד תוקד זה התורה שנק' אש והגית בו יומם ולילה.

And this is the meaning of "a perpetual fire shall burn [on the altar]" — this is the Torah, which is called "fire," and "you shall meditate in it day and night" (Yehoshua 1:8).

The constant altar-fire alludes to Torah, itself called fire, to be kindled continually through learning day and night.

ובזוה"ק בפסוק זה.

And in the Zohar HaKadosh on this verse:

The Sefas Emes now cites the Zohar's comment on this very verse about the perpetual fire.

עבירה מכבה מצוה ואין עבירה מכבה תורה.

"A sin extinguishes a mitzvah, but a sin does not extinguish Torah."

An aveirah can snuff out the "light" of a mitzvah, but it has no power to extinguish the light of Torah.

פי' דתורה אור הוא גוף האש ושם אין כיבוי.

The explanation is that Torah is "light" — it is the very body of the fire — and there there is no extinguishing.

Torah is the essence of the flame itself ("Torah ohr," Torah is light), and the core of fire cannot be put out.

כי כל דבר פסולת אינו יכול לכבות גוף האש.

For no waste/dross (pesoles) can extinguish the body of the fire.

Impurities and debris cannot quench the fire's actual core; if anything, the fire consumes them.

אך מכבה נר מצוה.

But it does extinguish the "candle of the mitzvah" (ner mitzvah).

The mitzvah is compared to a candle ("ner mitzvah," Mishlei 6:23), and a candle's flame can indeed be put out.

כמו הנר שמתלכלך באיזה דבר נדבק בו וגורם ג"כ שלא יוכל האש לשלוט שם ומתכבה אח"כ.

Like a candle that becomes soiled when some substance sticks to it, which also causes the fire to be unable to take hold there, and it is then extinguished.

When grime clings to a candle, it prevents the flame from catching and eventually snuffs it out — so too sin clings to a mitzvah and can extinguish its light.

אבל בגוף האור אין ליכלוך מכבה.

But in the body of the light itself, no soiling can extinguish it.

The essential light of Torah, however, is immune; no impurity can ever dim it.

ואמר כי הת"ח המצוה תורה הוא אצלם.

And he says that for talmidei chachamim, the mitzvah is "Torah" for them.

For a true Torah scholar, even his mitzvos are infused with the light of Torah — they are not mere external acts.

פי' כי השכל והדעת הוא האור משא"כ העושה מצות אנשים מלומדה אין בו גוף האור כנ"ל.

The explanation is that the intellect and the da'as is the "light," whereas one who performs mitzvos as "a commandment of men learned by rote" (mitzvas anashim melumadah, Yeshayahu 29:13) has no body of light within it, as above.

The light is the conscious understanding and da'as invested in a mitzvah. A mitzvah done by rote, without inner intent, lacks that essential light and so can be extinguished by sin like a candle.

וזה אין ביעור חמץ אלא שריפה.

And this is "the destruction (biur) of chametz is only by burning."

The Sefas Emes connects this to the halachic view that chametz (a symbol of the yetzer hara) is properly eradicated by fire.

אעפ"כ איתא בודקין לאור הנר כו' יפה לבדיקה כו'.

Even so, it is taught that "we search [for chametz] by the light of a candle," and that [candlelight] is good for the search (bedikah).

Yet the searching for chametz is specifically done by candlelight, which Chazal say is best suited for the bedikah.

פי' שאמת הביעור הוא רק באור ואש התורה.

The explanation is that the true destruction (biur) is only through the light and fire of the Torah.

Final eradication of the inner "chametz" — the yetzer hara — can only be accomplished by the powerful fire of Torah itself.

אבל הבדיקה הוא ע"י התדבקות האור תורה במצות.

But the searching (bedikah) is through the attachment of the "light of Torah" to the mitzvos.

The detective work of finding the hidden chametz, however, is done by the "candle of the mitzvah" — the light of Torah as it attaches to and illuminates one's mitzvos.

כי בתורה עצמו לא יראה ולא ימצא שם מגע סט"א כלל.

For in the Torah itself, "it shall not be seen and shall not be found" (the language of removing chametz) — there is no contact of the sitra achra at all.

Pure Torah is utterly untouched by the "other side"; the yetzer hara has no foothold there, so there is nothing to search out within Torah itself.

לכן הבדיקה באור הנר דייקא והביעור באש:

Therefore the searching is specifically by the light of the candle, and the destruction is by fire.

Hence the two stages: the "candle of the mitzvah" is used to locate the chametz (the yetzer hara at the boundary where it clings to deeds), while the consuming "fire" of Torah is what finally destroys it.

Summary: The olah atones for sinful thoughts, and the Torah hints that every evil thought "rises up" only so that it can be consumed in its designated "fire of a mitzvah" — for fire softens even the iron of the yetzer hara, which is how one serves Hashem "with both inclinations." Torah is the very body of the fire/light and can never be extinguished, but a mitzvah is like a candle whose flame sin can snuff out — unless, as for a talmid chacham, the light of Torah and da'as fills the mitzvah. This is mirrored in bedikas chametz: the inner yetzer hara is finally destroyed only by the fire of Torah, but it is located and searched out by the "candle of the mitzvah," since Torah itself is wholly untouched by the sitra achra.