I'd like to put together two famous midrashim, to come away with a beautiful lesson in Ahavat Yisrael.
The first midrash, which we've mentioned before, is that the Arba Minim/the four species correspond to four types of Jews.
One of them, the Etrog, has taste and smell, which corresponds to a Jew who has Torah (which is taste) and good deeds ( which is smell).
The Lulav, which comes from a date palm. It has flavor (from the date) but no smell, corresponding to our Jew who learns Torah, but does not do good deeds. Our next Jew is the Hadas, that has a good smell but doesn't have any flavor or any fruit. And that's why it says Esther is Hadassa. Because a lady’s job is to do maasim tovim/ good deeds, not necessarily to learn Torah, therefore she doesn't have the fruit.
And lastly, we have the Arava that has no taste and has no smell; that's the Jew that doesn't have either Torah or good deeds.
We put all four species together and that creates the unity of Jewish people.
Then there's another midrash that says that the four species correspond to four main organs in the body. The Lulav, which stands tall, corresponds to the spine, the Etrog, the pri etz hadar/ the beautiful fruit symbolizes the lev/ heart.
A “Lev Tov encompasses everything”
The Hadassim that look like eyes correspond to our eyes. And the Aravot are our lips. And the Aravot become wilted first because our lips are the things that get us into the most trouble.
“Life and death is the hands of the tongue.”
So those are the four species as symbols of the four organ parts of the body.
And now we take the next leap, which is that if we view these four species as one body (that's what these species symbolize- Each organ has its own function and together they create the human body), then our four types of Jews also create one body, called the Jewish people.
And that's the Mussar takeaway. The Yerushalmi tells us that antidote for Sinat Hinam is to realize that we're all one body. And just like if the right heel stubs the left toe, the left hand doesn't go and stab the right heel for stepping on the left toe. It's all one body, that would be ludicrous.
So too, the Jewish people are one body. So these two midrashim link together, looking at the four species as organs in a body, and the four different types of Jewish people, in a sense, also as organs of one body- the body of the Jewish people. That's the Achdut/unity lesson that we take from the four species, as it pertains to being a human body. Have a wonderful day and a Hag Sameach.