The reason behind the Mitzvah of Shemita:
Within the Talmud, and Rishonim, we find several reasons recorded regarding the purpose of the Mitzvah of Shemita.
- To emphasize that everything belongs to Hashem: The Mitzvah of Shemita publicizes to the Jewish people that everything belongs to Hashem and in the end will return to Him, and teaches us that we should not feel pride of the greatness of our land in a way that makes us forget the yoke of heaven.
- Commemorate creation: The purpose of the Mitzvah of Shemita is for one to be constantly reminded of creation and contemplate that Hashem created the world in 6 days. Thus, it is similar to the Mitzvah of Shabbos.
- Charity: The purpose of Shemita is for there to be a set year in which one is to have mercy on paupers and distribute them produce for free.
- Reminder of the seventh millennium: It is a reminder of the future events that will occur, of the time when we will merit eternal rest [in the seventh millennium].
- Reminder of death: The Mitzvah of Shemita reminds one that he only lives for a span of seventy years that teaches him that he should use his time wisely.
- Bitachon: Alternatively, the purpose of the Mitzvah of Shemita is in order for one to strengthen his Bitachon [trust] in Hashem.
- Compromise: Alternatively, it is to teach one the attribute of giving and compromise.
- Land rejuvenation: Alternatively, it is for the land to rest from its constant production in order for it to be able to continue to produce vegetation in the future years.
Sparks of Kabala
The elevation of Malchus:
During the Shemita year the Sefirah of Malchus is elevated, similar to the elevation that occurs on Shabbos. It is for this reason that it is forbidden to work the land during Shemita, similar to the law on Shabbos. Furthermore, this is a cause for Simcha, joy, during this year. It is for this reason that the Tikkun of Rachel is not recited the entire year during Shemita.
 See Halichos Shevi’is [Oz Vehadar] Introduction p. 26-27
 Sanhedrin 39a; Rashi ibid; Rabbeinu Bechayeh Vayikra 25b; Chinuch Behar Mitzvah
 Rashi ibid
 Chinuch Mishpatim Mitzvah 84 (69) “The purpose of this Mitzvah is for us to set in our hearts and impress within our minds the concept of the creation of the world that in six days Hashem created the Heavens and earth.”; Sefer Habatim 130; Abarbanel Vayikra 25:1
 See Even Ezra Vayikra 25:2
 Rambam Moreh Nevuchim 3:39
 Ramban Behar 25:2 “The days of the week hint to the creation of the world while the years of Shemita hints to the future years of the world [that we will reach a state of Olam Haba, eternal Menucha]. One who denies it is like one who denies the creation”; Rabbeinu Bechayeh Vayikra 25:2; Abrabanel
 Akeidas Yitzchak Shaar 69; Abarbanel ibid
 Keli Yakar Behar; Chinuch ibid “It also adds to one’s trust in Hashem”
The Keli Yakar ibid records the other reasons mentions by the Chinuch and Moreh Nevuchim and negates them for reasons mentioned there. He concludes that “I say that the reason for this Mitzvah is in order to root within the Jewish people the attribute of trust [Bitachon] and faith in Hashem. Hashem was worried that the constant preoccupation with the working of the land will cause them to forget G-d and they will think that it is their own efforts that has given them prosperity and blessing, and that the world works based on nature. They will think that they own the land, and they are the owners and no other. Therefore, Hashem removed us completely from the natural order. This is a clearer and better reason than all the other explanations and it is for this reason that such a severe punishment of exile is meted out for one who transgresses, as it is a lack of faith in Hashem and a lack of belief in His ability to perform a miracle and provide them their sustenance. The earth itself will also be upset for it not being rested as it desired that through it the Jewish people add in their faith in G-d.”
 Chinuch ibid “It also helps one acquire the attribute of compromise and letting go”
 Moreh Nevuchim 3:39 “It is to benefit man that the land adds to its grain and strengthen its soil by resting”, brought in Keli Yakar ibid; However, see Akeida Shaar 69 and Abarbanel Vayikra 25:1 and Keli Yakar ibid who question this reason
 Kaf Hachaim 581:75