… the long straight palm branch represents the spine. The myrtle leaf, which is a small oval, represents the eye. The willow leaf, a long oval, represents the mouth, and the etrog fruit represents the heart. All of these parts have the potential to be used for sin, but should join together in the performance of mitzvot (commandments, “to do good”).
… the etrog, which has both a pleasing taste and a pleasing scent, represents Jews who have achieved both knowledge of Torah and performance of mitzvot. The palm branch, which produces tasty fruit, but has no scent, represents Jews who have knowledge of Torah but are lacking in mitzvot. The myrtle leaf, which has a strong scent but no taste, represents Jews who perform mitzvot but have little knowledge of Torah. The willow, which has neither taste nor scent, represents Jews who have no knowledge of Torah and do not perform the mitzvot. We bring all four of these species together on Sukkot to remind us that every one of these four kinds of Jews is important, and that we must all be united.