In 1965, the Rebbe introduced a novel way of understanding Rashi’s commentary to the Torah through a series of principles and tools. Over the years, they were augmented and applied across hundreds of studies on Rashi. An exemplar of this approach is the Rebbe’s treatment of what appears to be the simplest of comments from Rashi on the first verse of the Parshah of Metzora.

The metzora is sometimes translated as a “leper,” although for the most part the spiritual affliction of tzaraat bears no resemblance to leprosy. It is a group of conditions—involving mostly reddening or whitening—that appear on a person’s body, clothes or home. The Torah delineates a complex set of rules to determine if a person is a metzora,1 and the consequences of a positive diagnosis are serious: the metzora is ritually impure and must be quarantined until the symptoms are declared to be lifted.2 Then, the metzora must bring an offering consisting of two small birds, a strand of scarlet wool, a piece of cedarwood and a bunch of hyssop stalks.

This is how the offering is described in the opening verse of the portion of Metzora:

“This shall be the law of the metzora on the day of his purification; let him be brought to the kohen.”3

Rashi cites the words “This shall be the law of” and comments: “This—the fact that the Torah says ‘on the day of his purification’—teaches us that we do not purify [the metzora] by night.”

Evidently, Rashi feels that the words he cited from the verse justify a new rule that restricts the purification to the daytime. Now, the words upon which Rashi bases his comment, “This shall be the law of,” do not seem to indicate any preference for day or night. So how does that teach us this new rule?

Of course, the following words are “on the day of his purification,” which do use the word “day” in relation to the metzora’s purification and which could presumably tell us something about the timing of the purification. Indeed, the original source for this ruling is the Midrash called Torat Kohanim,4 which does cite “on the day of his purification” as the proof text.

Why does Rashi not do the same? Instead, Rashi quotes words from the verse that do not seem to prove anything, while omitting the words that appear to validate his comment!

The Rebbe’s unique approach to Rashi involves stepping back and re-examining basic assumptions. Through a shift in understanding, the problem melts away.

Why, the Rebbe asks, do we assume that day means daytime? When we say “day,” do we always mean during the hours that the sun shines? If I say, “Every day, I spend half an hour studying,” does that preclude me from doing so after sundown? Of course not. Likewise, in the Torah, “day” often simply refers to a single 24-hour period. We need to look no further than the opening sentences of the Torah: “It was evening and it was morning, day one.”5 Clearly, the words “day one” include both the evening and the morning.

In fact, the word “day” is so fluid that the Torah uses it when describing events that took place entirely at night: “On the day I smote the Egyptian firstborns in the Land of Egypt”6 refers to an event that the Torah tells us happened at the stroke of midnight. So it turns out that “day” does not necessarily mean daytime.

Now we have a major problem: If “day” can also mean “night,” how does Rashi know that the word “day” in our verse is teaching us that the purification must be by day and not by night?

That, explains the Rebbe, is why Rashi did not cite the words “on the day of his purification” as his proof-text, because they prove nothing. It could say “day” and mean “night.” Instead, Rashi deliberately cites the words preceding that, “This shall be the law of,” because surprisingly this does teach us that the word “day” is exact and means only during daytime.

How so?

Read again the opening words of the Parshah, “This shall be the law of the metzora,” and ask yourself why those words are even needed, given that the previous 59 verses discuss nothing but the laws of the metzora. The Torah could just as well have omitted those words entirely and begun with the words, “On the day of his purification, he shall bring ... ”

We must conclude that those seemingly redundant words are there for a reason. But what?

Rashi supplies the answer: The opening words, “This shall be the law of the metzora,” are there to teach us how to interpret the next words, “on the day of his purification”—literally during the daytime.

How do we know this? Because all the words in the opening phrase imply exactitude.

Let us examine each one in turn. “This” implies a degree of precision. If I tell you to “do it this way” or to go in “this direction,” I am excluding another way or direction. The next words, “shall be,” also suggest specificity. If I say, “this is how things shall be,” you know this means a clear preference for a particular course of action. The words “the law of” imply rigidity and definition. If the words “on the day of his purification” are preceded by three phrases that all imply exactitude, it follows that “day” is to be read literally. So it turns out that the words Rashi cites from the text are in fact the basis for his comment.

There is a moral lesson here for us: The “day of purification” is preceded by “This is the law of.” What can this teach us? That when one seeks purity and holiness, the sole path to achieving this goal is through studying Torah (“the law”). Living as we do in a material reality, we are subject to impurity. Torah study lifts us out of the mundane and elevates us to a world of holiness and purity.