The epigram, "They tried to kill us. We survived. Let's eat!" sometimes serves as a tongue-in-cheek synopsis of Jewish holidays: Passover, for example, recounts the original Jewish survival story in an extended banquet punctuated by four cups of wine. Similarly, Purim combines the story of Esther and Mordechai's victory over the evil designs of Haman with lots of festive eating and drinking.
Tu B'Shevat is different. Unlike Passover and Purim, it's not rooted in a biblical narrative, and there's no survival theme. Instead, it marks a day in the calendar, Tu B'Shevat, literally the 15th of the month of Shevat. In the Talmud, the day is called Rosh Hashanah Ha'llan, or New Year for the Tree, and marks the beginning of the agricultural cycle for trees as well as a deadline for Israelites to calculate the year's tithes (or offerings) of fruit they were required to bring to the Temple in Jerusalem. With the fall of the Temple and the end of tithing, the date lost much of its importance, but the holiday remained on the Jewish calendar.
Tu B'Shevat found a second life some thousand years later with a new ritual: a seder. Conceived by the Kabbalists of 16th-century Safed, the Tu B'Shevat seder was viewed as a tikkun (repair) to bring human beings closer to spiritual perfection. The seder is structured around four cups of wine and has a prescribed order to the meal, which consists of fruits and nuts found in the Land of Israel. It's interspersed with readings and kavanot (spiritual meditations) from biblical, rabbinic and Kabbalistic texts that are designed to draw symbolic parallels between the gift of the physical fruits of trees and the gift of the spiritual Tree of Life--the Kabbalists' mystical conceptualization of the presence of God in the world.
Described in a 50-page pamphlet published in Venice in 1728 and entitled "Pri Etz Hadar" ("The Fruit of the Beautiful Tree"), the seder foods symbolize God's creations in ascending order, from the material to the spiritual plane. The first fruits and nuts to be served have inedible shells, such as pomegranates or almonds, and represent the physical world in which protection and defenses are necessary. Fruits with inedible cores--such as apricots or olives--follow, to recall both physicality and inner emotions that need protection. The third group are fully edible fruits such as figs or blueberries. They stand for the highest level of physical and spiritual perfection achievable in the corporeal...