Science Found the Lemon's Source. The Torah Put It in Your Hand First

by Dr. Yosef Wolf

Every orange, lemon, and grapefruit in your kitchen likely originates from three wild fruits. One of them is the esrog. In 2018 an international team of geneticists read the DNA of sixty citrus samples. Most came out as hybrids, each a child of two parents; the ones you buy trace back to mandarin, pummelo, and citron (the esrog). The same team confirmed that a lemon is a citron crossed with a sour orange (Wu et al., 2018). For perhaps a thousand years the citron was the Mediterranean's only citrus; the lemon came later. This Sukkos you hold the lemon's genetic parent, פרי עץ הדר (pri eitz hadar, "the fruit of the hadar tree," Vayikra 23:40). Long before any lab, the Gemara identified it by two signs.

One is a tree "whose wood tastes like its fruit"; the other, a fruit that "dwells on its tree from year to year" (Sukkah 35a). The Alter Rebbe reads that fruit as the source of the souls of the righteous, who stay on their tree (Likkutei Torah, Sukkos). On the mystical level, Ramban reads this fruit as the fruit of Adam's sin at the Tree of Knowledge. Adam took it alone; on Sukkos a Jew lifts it with the lulav, hadassim, and aravos to obtain Hashem's favor (Ramban, Vayikra 23:40). That fruit is in your hand this week. Yet a fruit can look like an esrog and not be one.

An esrog that is מורכב (murkav, grafted with another tree) "is not an esrog at all but a creature of its own," rules the Alter Rebbe (Shulchan Aruch HaRav, Orach Chaim 648:31). In 2005 botanists in Italy, Morocco, and Israel checked twelve esrog varieties for DNA from four other citrus, the lemon among them. They found none; every one came back unmixed (Nicolosi et al., 2005). Yet DNA reveals only a cross, two species mixed in the seed. A graft, a branch tied onto another tree, leaves no trace in the fruit's DNA.

The lemon in your kitchen never chose to be mixed. But a person chooses...one habit at a time. A borrowed habit can take a Jewish one's place, a gratitude journal where Modeh Ani used to be, and from the outside nothing looks different. Modeh Ani thanks Hashem each morning for returning your soul; Sukkos thanks Him for a year of crops, set "when you have gathered in the yield of your land" (Vayikra 23:39). Over Sukkos, say Modeh Ani first and only then let the journal follow. When Moshiach comes, the nations will go up to Yerushalayim to celebrate Sukkos (Zechariah 14:16), a whole world giving thanks at the festival of a fruit that never mixed.