Siman - Eruvin Daf 27
- אין למידין מן הכללות
The opening Mishnah of the third perek states, בכל מערבין ומשתתפין חוץ מן המים ומן המלח – We may make an eruv (meaning, an eruvei techumim or a shitufei mavo’os) with anyfood, except for water and salt.
Rebbe Yochanan said, אין למידין מן הכללות, - we cannot learn from general rules, אפילו במקום שנאמר בו חוץ – even when the rule concludes by saying, “except”, and specific exceptions are listed, it is not absolute.
Rebbe Yochanan made this statement in reference to a Mishnah in Kiddushin that says that, כל מצות שהזמן גרמא אנשים חייבין ונשים פטורות – All time-bound positive mitzvos, men are obligated in and women are exempt, -ושלא הזמן גרמא אחד נשים ואחד אנשים חייבין And mitzvos which are not time-bound, both women and men are obligated in. This rule is not absolute, because women are indeed obligated in the mitzvos of matzah, simchah and hakhel, even though they are מצות עשה שהזמן גרמא - and they are exempt from Talmud Torah, p’ru u’rvu , and pidyon haben, even though those mitzvos are not time-bound.
Similarly, our Mishnah (as pointed out later in the Gemara) does not mention that one may also not make an eruv with truffles or mushrooms.
- Buying saltwater with maaser sheini monies
The Mishnah also stated, הכל ניקח בכסף מעשר חוץ מן המים ומן המלח – All types of food may be purchased with maaser sheini monies except for water and salt. In the Gemara there is a machlokes regarding if one can purchase a mixture of salt and water with maaser sheini money .
• One holds that one may buy saltwater with maaser sheini. Rashi explains that since salt water is used as a dip for bread, it qualifies as a significant food. The other holds that salt water cannot be purchased with maaser sheini because, פירא בעינן – a fruit (or something similar to it) must be purchased.
• The one who holds that salt water may be purchased with maaser sheini, would certainly permit using salt water for an eruv. The Ritva explains that maaser sheini would have greater restrictions since it is a d’Oraysa and an eruv is a d’Rabbanon .
- הבלעה
The Gemara taught that Rebbe Yitzchak who says that one can buy salt water with maaser sheini, only allowed that if there was oil mixed into it. The Gemara asks that one can buy maaser sheini with oil alone, so what is the chiddush that one may purchase maaser sheini with salt water mixed with oil? The Gemara answers that the chiddush is the concept of הבלעה, which means that one may pay more for the oil, due to the value of the mixed in water and salt, even though the water and salt themselves do not become maaser sheini. The Gemara brings a Baraisa that teaches the source for this concept, that Ben Bag Bag said that the extra word בבקר in the passuk regarding purchasing foods with maaser sheini teaches that we may purchase cattle, and pay extra for its hides, even though the hides do not become maaser sheini.
