The Thirty-Nine Forbidden Works
The Torah states (Shemot, 20): “Remember the day of Shabbat to sanctify it. For six days shall you work and perform all your work and the Seventh day shall be Shabbat for Hashem, your G-d, you shall not perform any work etc. For six days did Hashem create Heaven and Earth, and he rested on the Seventh day. Therefore, Hashem blessed the Shabbat and sanctified it.” The Torah warns us about Shabbat observance twelve times, for this serves as the basis for our belief in the creation of the world. Our Sages said: “Whoever keeps the Shabbat, it is as if he has fulfilled the entire Torah. Whoever desecrates the Shabbat, it is as if he has denied in the entire Torah.” The reason for this is, as we have already established, that this serves as the basis of our belief.
The “work” prohibited by the command of Hashem on the day of Shabbat is any work that was performed in the Mishkan (Tabernacle) during the time the Jewish people were encamped in the desert. The Mishnah (Shabbat 73a) delineates all the forbidden types of work and these amount to thirty-nine forbidden types of work.
The Forbidden Work of “Selecting”
One of the well-known types of forbidden works on Shabbat is “selecting.” It is imperative that every member of the Jewish nation be proficient regarding all of the practical laws of the forbidden work of selecting, for one can easily perform a work that is forbidden on Shabbat, as we encounter this forbidden work quite frequently.
The main form of forbidden selecting on Shabbat is when this is done through a sieve or a strainer, for instance, if one takes flour which has other things mixed into it and sifts the flour in a sieve until the flour pours out of the holes of the sieve and the waste stays in it; this is the forbidden work of selecting on Shabbat and one who does so is liable for Shabbat desecration. Any selecting that is forbidden on Shabbat entails two items: One type entitled “food” and one type entitled “waste.”
What Constitutes “Waste” Regarding Forbidden Selecting
When we say that selecting food from waste or waste from food is forbidden on Shabbat, this does not necessarily entail actual “food” and “waste”; rather, any food which one desires at the present time is considered “food” as opposed to other food that one does not desire which is considered “waste”.
For instance, if one has a plate before him containing two different types of legumes or seeds, such as sunflower seeds and watermelon seeds, and both are good and edible, however, at the present time, one only wishes to eat the watermelon seeds and one selects all of the sunflower seeds and places them in another plate, this constitutes the prohibition of selecting, since the sunflower seeds are considered “waste” for this individual as he does not want them at the present time and the watermelon seeds are considered “food” since he desires only them at the present time.
Summary: Selecting is forbidden on Shabbat. Thus, if one has a plate with two types of food, such as sunflower seeds and watermelon seeds or strawberries and cherries, before him and one only wishes to partake of only one of them, one may not remove the food that one does not want from the plate and leave only the food that one does want. Clearly though, there are permissible ways to select on Shabbat, as we shall, G-d-willing, explain in the following Halachot.