Parshat Tazria is about science. Ancient science, yes, but science nonetheless. Most of Tazria deals with the question of what happens when someone demonstrates symptoms of the skin disease tzara’at. Specifically, the question at the heart of the parsha is, how does the priest identify tzara’at? The diagnosis is outlined, as is the treatment. The main action thus falls on the kohen, the priest, who resembles a medical doctor or scientist as he categorizes the natural phenomenon before him: Is this disease tzara’at or not?

Observation and categorization are the essential moves of the scientist. What makes modern science so powerful is its ability to place the things of nature into conceptual categories. Categorization allows us to understand, to discuss, and to theorize. If we can’t name it, we can’t talk about it. Yet the move of categorizing involves not only understanding, but also control: when we place a label on a phenomenon, we feel as though we control it. And thus naming, categorization, carries with it enormous power and responsibility.

Perhaps this is why the Rabbis connected tzara’at to lashon hara, gossip. The Torah, of course, tells the story of Miriam, who spoke ill of her brother Moses and was stricken with tzara’at. It even instructs to remember what happened to Miriam. The sense of power over others we experience when we gossip about them is answered with the powerlessness of becoming the object of someone else’s observation, the gaze of the scientist. Just as we sought to name and dominate another, we are reminded that such power is not ours, and that we are just as frail and powerless as the ones over whom we projected our power.

Yet observing, naming, categorizing, generalizing—these moves are essential to human life. They are the basis of language, the roots of how we interact with the world. We can’t help but talk about things and people. If we tried to stop, we would cease thinking. So where is the medium?

One answer comes in the special Torah reading we add on this Shabbat Hachodesh—the Shabbat preceding the month of Nisan, in which Passover takes place. “This shall be for you the first of the months,” God instructs Moses and Aaron. From this passage, the Rabbis inferred that time, the calendar, is a human activity: we must be the ones to proclaim the new moon. In fact, the Talmud relates that so great is the human power and responsibility to name time that God defers to human beings when it comes time to sit in judgment on Rosh Hashanah. If the rabbinic court has not proclaimed the new moon, then the heavenly court packs up its things and returns the next day, for it is the human calculation that is primary.

At the same time, of course, the human power over time is far from absolute. We do not have the power to change the day of Shabbat (despite the attempts of some early Reform Jews to move Shabbat to Sunday). We cannot add a day to the week. Shabbat, which recalls God’s creation of the world, reminds us of the world that we inherit, the world we are born into, the world whose categories and names we must accept. The festivals, by contrast, remind us of the world we create, the world whose categories and names we generate. The festivals evoke our human power and responsibility, Shabbat reminds us of its limits.

Shabbat shalom.