The Mishnah taught that the absence of one the four kinds of plants used for the lulav — the palm-branch, the etrog, the myrtle, or the willow — invalidates the others. The Gemara explained that this is because says, "And you shall take," signifying the taking of them all together. Rav Hanan bar Abba argued that one who has all of the four species fulfills the requirement even if one does not take them in hand bound together. They raised an objection from a Baraita that taught: Of the four kinds used for the lulav, two — the etrog and the palm — are fruit-bearing, and two — the myrtle and the willow — are not. Those that bear fruit must be joined with those that do not bear fruit, and those that do not bear fruit must be joined with those that bear fruit. Thus a person does not fulfill the obligation unless they are all bound in one bundle. And so it is, the Baraita taught, with Israel's conciliation with God: It is achieved only when the people of Israel are united as one group.