Shabbat 34b (לד:) — the Talmud in English

And Rava said:

Why did they say that one may not insulate with something that adds heat

such as olive-pomace and manure,

even while it is still day—

It is a decree lest one insulate it in hot ashes

[which are ashes mixed with coals], because

there is a coal among them.

Abaye said to him: Then let him insulate it

even in ashes containing a coal; what of it?! For while it is still day there is no concern lest he come to stir the pot, since at that time he is indeed permitted to heat it

? Rava said to him:

It is a decree lest

he insulate, while it is still day, a pot that has not finished cooking, and

stir the coals

after nightfall, so that it will cook on Shabbat. Therefore, they decreed that one may not insulate, while it is still day, even a pot that has finished cooking completely.

And we find in a Mishna below that the Sages decreed that one may not leave a pot on the fire, even if it has finished cooking completely, until he rakes away the coals or until he covers them with ash, so that he will not come to stir the coals. Therefore, it is prohibited to insulate in ashes containing a coal. The Sages also decreed that one may not insulate with anything that adds heat, even when there is no coal there, so that one will not come to insulate in ashes.

The Sages taught:

twilight

is:

a.

A doubt

whether it contains both

some of the day and

also

some of the night.

b.

A doubt whether it is entirely day.

c.

A doubt whether it is entirely night.

Therefore,

one treats it stringently as belonging to both days.

As will be explained below.

And what is twilight?—

From sunset, as long as the eastern horizon is reddening,

when the redness of the sun is visible in the clouds.

When the lower part has darkened,

has blackened, while

the lower

part of the sky

and

still

has not darkened

the

upper

part, because of the rays of sunlight directed upward—this is

twilight.

Only when

the upper part has darkened,

has blackened as well, and

the upper part is equal to the lower—

that is night, the statement of Rabbi Yehuda.

Rabbi Nehemiah says:

The duration of twilight is

the time it takes a person to walk half a mil from sunset,

and then it is night.

Rabbi Yosei says: Twilight

is an extremely brief period,

like the blink of an eye,

like the time of a relaxed blink.

This

night

enters, and this

day

departs.

And it is impossible to determine it precisely

because of its brevity. Before that, it is fully day.

The Master said: One treats it

twilight,

stringently as belonging to both days.

For what halakhic purpose?

Rav Huna, son of Rav Yehoshua, said: With regard to the ritual impurity

of a zav.

A zav is a man who experienced a discharge from his body twice, either on one day or on two consecutive days. He is impure until seven clean days without a discharge have passed, after which he immerses in spring water and becomes pure.

Likewise, if he experienced a discharge only once, but the discharge continued during a period that encompassed two consecutive days—for example, it began shortly before the end of the day and continued into the night belonging to the following day—it is considered as though he experienced two sightings on two consecutive days. He is therefore impure as a zav.

And if he experienced three sightings of a discharge on one day, or on two or three consecutive days, he is obligated to bring the offering of a zav, and he may not enter the Temple or eat sacrificial meat until he brings his offering.

As we learned: One who

experienced a

sighting

of a discharge on

two days, during twilight,

for example, he experienced the first discharge during the twilight following the first day and the second during the twilight following the second day—

he is

in a state of uncertainty with regard to impurity.

For, on the one hand, it is possible that the two sightings occurred on two consecutive days, on the first day and the second day, and he became impure.

For it is possible that the twilight of the first day was entirely part of the first day, while the twilight of the second day was entirely part of the second day; consequently, he experienced two sightings of a discharge on two consecutive days.

Likewise, it is possible that the twilight following the first day was already the night of the second day, whereas the twilight following the second day was also part of the second day; consequently, he experienced two sightings on one day.

On the other hand, it is possible that he experienced the two sightings on two nonconsecutive days: the twilight following the first day was part of the first day, while the twilight following the second day was already the night of the third day. Consequently, the second day was a day free of a sighting, separating the two days on which he experienced the sightings, and he does not thereby become a zav.

And

likewise, he is uncertain with regard to his

obligation to bring an offering.

For it is also possible that the first sighting occurred on the first day, while the second occurred over both the second and third days, and is considered as two sightings on two consecutive days. Consequently, he experienced three sightings on three consecutive days and is obligated to bring an offering.

Since the matter is uncertain, he brings a bird sin-offering brought in a case of uncertainty. That sin-offering is pinioned, and its blood is sprinkled on the altar, but it is not eaten. For perhaps he is not a zav who is obligated to bring an offering; in that case, once it has been pinioned in the manner of a sacrificial bird rather than slaughtered in the manner of an unconsecrated bird, it is an animal carcass.

And if he

experienced

one sighting on

one day during twilight—

he is

in a state of uncertainty with regard to impurity.

For perhaps the sighting occurred both on the preceding day and on the night of the following day, and is considered two sightings; or perhaps it was one sighting on one day בלבד.

The Gemara now explains the time of twilight mentioned in the beraita:

And we raised a difficulty:

This matter itself is difficult.

You said: What is twilight?—

From sunset, as long as the eastern horizon is reddening.

This apparently indicates that it is the period during which even the lower part of the dome of the sky has not yet darkened.

But

when the eastern horizon is no longer reddening, and already

the lower part has darkened, and

although it still

has not darkened in the upper part—

it is night.

And

if

the tanna had repeated,

later in the beraita:

The lower part has darkened but the upper part has not darkened—

it is twilight?!

Rabba said that Rav Yehuda said that Shmuel said: Combine

the statements,

and teach

as follows: a.

What is twilight?—

From sunset, as long as the eastern horizon is reddening.

b.

And when the lower part has darkened and

still

the upper part has not darkened—

it is also twilight.

c.

When the upper part has darkened and is equal to the lower—

it is night.

And Rav Yosef said that Rav Yehuda said that Shmuel taught it as follows:

a.

From sunset, as long as the eastern horizon is reddening—

it is day.

b.

When the lower part has darkened but the upper part has not darkened—

it is twilight.

c.

When the upper part has darkened and is equal to the lower—

it is night.

And they followed

Rabba, who extends the duration of twilight and includes within it the period of “from sunset, as long as the eastern horizon is reddening,” and Rav Yosef, who shortens the duration of twilight and limits it only to the period when the lower part has darkened but the upper part has not—

according to their respective approaches.

As it was stated: The measure of twilight—

how much is it?

Rabba said that Rav Yehuda said that Shmuel said:

The time it takes to walk

three parts of a mil.

And we raised a difficulty:

What does “three parts of a mil” mean?

If you say three halves of a mil,

three half-mils—then

let him say: one and a half mil.

Rather, three thirds of a mil,

three one-third-mils—then

let him say: one mil.

Rather: three quarters of a mil,

three quarters of a mil.

And Rav Yosef said that Rav Yehuda said that Shmuel said:

The time it takes to walk

two parts of a mil.

And we raised a difficulty:

What does “two parts of a mil” mean?

If you say two halves of a mil,

two half-mils—then

let him say: one mil.

But rather, two quarters of a mil—

then

let him say: half a mil.