Vessel Impurity, Eye Blemishes, and Personal Rulings

How Tosafot harmonizes conflicting rules on earthenware defilement, defines permanent blemishes, and limits self-serving halakhic rulings.

Defilement From an Earthenware Vessel's Back

In Bekhorot 38a, the Gemara analyzes how ritual impurity spreads through vessels. By Torah law, an earthenware vessel (כלי חרס) contracts impurity exclusively through its interior airspace, never from its exterior back (גב). However, the Gemara states that once an earthenware vessel's inside becomes impure, its exterior also becomes impure. Rashi notes that this principle serves as the model for vessels purified by rinsing (כלי שטף) that become impure through liquids.

Tosafot points out an immediate difficulty against the textual version of Rabbeinu Shmuel in Shabbat 16a, which indicates that an earthenware vessel does not defile from its back under any circumstances. How can our Gemara declare that its back becomes impure?

Tosafot answers by distinguishing between receiving impurity and transmitting it. Quoting Torat Kohanim, Tosafot demonstrates that an earthenware vessel can never receive impurity from its exterior; however, once defiled from within, it defiles other things from its back.

שמטמא אחרים מאחוריו ואינו מיטמא מאחוריו

for it defiles other things from its back, yet it does not become defiled from its back. (Tosafot on Bekhorot 38a:7:1)

Can a Curable Condition Be a Blemish?

On Bekhorot 38b, the Gemara discusses eye defects that disqualify a firstborn animal (בכור). A floating white cataract is ruled to be a blemish, and the Gemara offers a mnemonic: ברקא (barka, white eye patches), which is known to be a blemish. Rashi explains that barka is a floating white condition that constitutes a blemish.

Tosafot asks a fundamental question: to permit slaughtering a firstborn outside the Temple, an animal must suffer from a permanent blemish (מום קבוע). Yet passages in Shabbat 78a and Gittin 69a outline well-known medical salves and kohl remedies for barka. If barka can be cured by medicine, how can the Gemara classify it as a permanent blemish?

Tosafot offers two resolutions. First, medical remedies are only effective in the earliest stages before the affliction becomes firmly set. Alternatively, any condition that does not heal on its own is halakhically deemed a permanent blemish, even if external human cures or surgical interventions can remove it.

ועוד יש לתרץ דהיכא דאין מתרפא מאליו חשיב מום

Furthermore, one can answer that wherever it does not heal on its own, it is considered a blemish. (Tosafot on Bekhorot 38b:3:1)

Scholars Ruling on Their Own Interests

The Gemara relates that Rabbi Shimon ben Yosei Lakonya instructed his student that a snail-shaped growth is a permanent blemish, allowing the student to inspect and permit Rabbi Shimon's own firstborn animal. The Gemara challenges this from Rav Huna: a scholar who issues a ruling is trusted only if he taught it prior to the practical incident (קודם מעשה), but not after the incident arises. Rashi explains that when a ruling is novel, we suspect he may have formulated it specifically to serve his personal interest,.

This rule seems overly broad, threatening to disqualify scholars whenever a legal principle touches their lives. Rabbeinu Tam clarifies that this suspicion applies strictly when the scholar has a personal need to act upon that ruling for his own benefit. If a scholar merely recites or teaches a halakha that happens to relate to his circumstances without deriving practical personal gain from it, his testimony remains fully valid.

אומר ר"ת דלא אמרי' הכי אלא היכא דצריך לאותה הוראה

Rabbeinu Tam says that we do not say this except where he has need for that ruling. (Tosafot on Bekhorot 38b:7:1)

Tosafot establishes that vessels transmit impurity outward even where they cannot receive it, conditions that cannot heal naturally remain permanent blemishes, and scholars are disqualified only when personally benefiting from their rulings.

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