Tafasta meruba lo tafasta

"Tafasta meruba lo tafasta" (Aramaic: תפשת מרובה לא תפשת, "If you have seized a lot, you have not seized") is a Talmudic idiom used to express the idea that when there exists the possibility of learning a particular law out from two sources, the law should be learned from the source that will provide the lesser stringency. [Talmud Chagigah 17a]

Terminology and meaning

The entire phrase actually expresses both the positive and negative directives: תפשת מרובה לא תפשת תפשת מועט תפשת - "If you have seized a lot, you have not seized; if you have seized a little, you have seized." The intended analogy is to one who grabs more than he can hold.

Explanation

The use of this concept is best explained with an example from the Talmud: [Talmud Rosh Hashanah 4b]

In comparison to the holidays of Passover and Sukkot, Shavuot is a relatively short Jewish holiday. This posed a problem in the times of the Holy Temple because there simply would not be enough time for the holiday sacrificial offerings of the entire nation to be sacrificed; Passover and Sukkot were seven and eight days, respectively, while Shavuot was but a single day. The Talmud explains that there was an extended period of time, referred to as "tashlumin" (period during which the remaining sacrifices could be completed), that was appended to Shavuot to make up for the relative shortness of the holiday.

The question is: for how long can the Shavuot holiday offerings be brought? With the presence of an extra mention of both Passover and Sukkot, both could be used to determine an equivalent period of time -- comparing Shavuot to Passover would yield a seven day period, while comparing it to Sukkot would yield an eight day period, and there is nothing pressing one choice over another.

The Talmud concludes that Shavuot is compared to Passover to yield a comparable seven day period to complete the sacrificial offerings. Why not compare Shavuot to Sukkot and gain an extra day? So the rule of "tafasta meruba lo tafasta" comes to show us that we cannot seize more than is certainly allowable. Either way the comparison is made (to the seven-day-Passover or the eight-day-Sukkot), Shavuot will reach at least a seven day period, but it is only with excessive seizure that an eighth day can be realized. Because this excessive seizure may be overstepping the bounds and there is no rationale to compare Shavuot to one over the other, we are forced to accept only the minimum seizure, leading in this case to a comparison of Shavuot to the seven days of Passover.

References