Nedarim 76a — the Talmud in English

But read the end of the beraita, -

and we raise an objection to this proof, for from the end of the beraita there is an opposite proof:

They said to Rabbi Eliezer -

the Sages challenged the words of Rabbi Eliezer, who proved in the Mishna that one may nullify before she vowed from the fact that one may nullify after she has already vowed:

And will you prove also from the fact that

if

we find that

one immerses an impure vessel

in order

to purify it, let one immerse

even

a vessel

that is pure, which

when it becomes impure

then its immersion will be effective

now to purify it?

But the law is not so, and immersion is effective for a vessel that is pure only to purify impure vessels.

And we learn from this that one may not prove from the fact that it is possible to annul something that has already taken effect that it should be possible to annul something that has not yet taken effect.

And the Gemara proves from the words of the end a proof opposite to our doubt.

We see from the objection of the Sages to Rabbi Eliezer that, according to Rabbi Eliezer, the law should be that immersion is effective even for a vessel that is pure, in order to purify it from future impurity.

And it is implied from the wording of the beraita, “when it becomes impure—to become pure,” that even if immersion for a pure vessel were effective, the vessel would become impure and afterward become pure.

And if so,

infer from it

that according to Rabbi Eliezer

the vows take effect

after the nullification and afterward are annulled.

And it is found that the words of the beraita contradict one another from the beginning to the end.

They said

the members of the academy resolve the contradiction in the beraita]:

The Sages were not established for them in the reasoning of Rabbi Eliezer

[they did not know what the method of Rabbi Eliezer was].

And this is what they said to him: What do you hold?

They challenged him, either way:

If you hold that they take effect

the vows

and are annulled

immediately

, let the vessel be your refutation -

the immersion of vessels will be difficult for your words.

And

if you do not hold that they take effect -

and if you hold that the vows do not take effect at all,

let the ritual bath be your refutation -

the ritual bath will be difficult for your words.

And therefore there is no proof for the doubt about which we were uncertain from the words of the Sages.

And we resolve it from a beraita.

Come and hear:

Rabbi Eliezer said to them

to the Sages [he proved to them that we say such a kal va-chomer].

The law is that if impurity touched seed that is sown in the ground, the seed does not become impure, and this law is derived by a kal va-chomer.

And as for impure seeds

that became impure before their sowing, their law is that

once he sowed them in the ground, they are pure

because this is learned from the verse, “that which he will sow—it is pure.”

Seeds that are

already sown and standing

at the time when they became impure,

all the more so

should they not become impure?

And we see that one may make a kal va-chomer from the fact that it is possible to annul something that has already taken effect.

And from this the Gemara proves concerning our doubt:

The law is that seeds sown in the ground do not become impure at all. And from the fact that Rabbi Eliezer compares the law of seeds to the law of nullification of vows,

infer from it

that Rabbi Eliezer holds that

they do not take effect

the vows at all after they have been nullified.

And the Gemara raises an objection to the view of the Sages:

And

do

the Sages not derive a kal va-chomer

such as this?

For it was taught: One might say that a person may sell his daughter

as a Hebrew maidservant even

when she is a young woman?

You say a kal va-chomer:

If

one already sold, she goes out

when she becomes a young woman,

one who is still

not sold -

is it not logical that she should not be sold

when she is a young woman?

And we see that even the Sages agree that one may make a kal va-chomer from the fact that it is possible to annul something that has already taken effect.