The ruling of Rebbi Eliezer seems to contradict a number of rulings
elsewhere in the Gemara. The Gemara earlier (29b) quotes Rav Ashi who states
that vinegar and Yayin Mevushal do *not* need two seals in order to remain
permitted. This implies that regular wine *does* need two seals. Rava in our
Gemara discusses exactly what constitutes a seal within a seal. Why does
Rava involve himself in a matter which is not relevant? Furthermore, Rav
himself says later (39a) that wine is something which is forbidden when it
has only one seal! How can we reconcile these Gemaras with the ruling of
Rebbi Eliezer?
(a) TOSFOS (DH d'Amar) quotes RABEINU TAM who answers that the Halachah
indeed follows the view of Rebbi Eliezer. All of the Gemaras quoted above
that seem to contradict this are not discussing wine left with a Nochri.
They deal with wine deposited with a *Jew* who is suspected of pouring wine
for Avodah Zarah. Since he is a fellow Jew, he is more comfortable with his
brethren and he thinks that they will definitely believe him when he says
that he did not tamper with the single seal of the wine. To ensure that this
does not happen, the Chachamim required a double seal for wine left with
this kind of Jew.
Tosfos finds this approach difficult, because those Gemaras make no mention
of a Jew who is suspected of idolatry. On the contrary, all of those Gemaras
seem to be discussing Nochrim!
(b) Tosfos explains that there is a difference between one who sends wine to
his friend using a courier who is a Nochri, and one who entrusts his wine
with a Nochri for safekeeping with intention to take his wine back with the
seal intact. When someone sends wine with a courier, the courier knows that
the intended recipient does not necessarily know exactly what the seal is
supposed to look like. Hence, he has no inhibitions about opening the single
seal, pouring some wine to Avodah Zarah, and fixing the seal. However, if he
knows that the owner himself will recognize that the seal was tampered with,
then he will be scared that his act of pouring the wine to his idol will be
discovered. In this case, one seal is enough.
Tosfos proves this from the wording of the Gemara. Rebbi Eliezer states his
ruling with regard to someone who deposits his wine with a Nochri. Usually,
a deposit is retrieved by the owner after a period of time has passed. On
the other hand, Rav Ashi is discussing vinegar and Yayin Mevushal that was
"b'Yad Akum," in the hands of a Nochri. This implies that the wine was sent
from one Jew to another via a courier who is a Nochri. RASHI (39b, DH
Asurim) explains that the case of Rav also involves sending the wine with a
Nochri messenger. This is why those cases require two seals for regular
wine.
(c) The RAN gives another explanation. The Ran writes that according to the
text of his Gemara, Rebbi Eliezer requires the Jew to have the key to the
house *and* that the wine should have a seal; *both* conditions are
necessary. This is also the text of the RACH, RIF, BEHAG, and other
Rishonim. Although the Ran at first gives credence to Rashi's text and
quotes Tosfos' second explanation, he also gives an explanation based on
this text. Rebbi Eliezer agrees that wine needs two seals. However, he
maintains that if the Jew has a key to the area where the wine is being
kept, this is also considered like a seal, even though it is not an actual
seal on the body of the wine barrel. The Rabanan argue that one needs two
seals on the wine barrel itself, and a key is not a seal at all. The ROSH
and RAMBAN also give this explanation according to the Rif and the Behag.