Answer #1: We learn from Achoso. Just like one's paternal and maternal sisters are forbidden, also both sisters of one's wife are forbidden.

Question: Why don't we learn from Dodaso, that only the paternal sister is forbidden?

Answer: It is more reasonable to learn from Achoso, since this Isur is due to himself, just like Achos Ishto.

Objection: It is better to learn from Dodaso, for the Isur comes through Kidushin, just like Achos Ishto!

Answer #2: Rather, we learn from Eshes Ach, since this Isur is due to himself and comes through Kidushin.

Question: What is the source regarding Eshes Ach?

Answer (Beraisa): "Ervas Eshes Achicha" is forbidden, for paternal and maternal brothers.

Question: Perhaps it applies only to paternal brothers!

Suggestion #1: Just like the Isur Achoso applies to paternal and maternal sisters, also here.

Suggestion #2: Or, perhaps we should learn from Dodaso, and only the paternal brother is included!

Decision: We should learn from the more similar case.

Suggestion #1: It is better to learn from Achoso (his own relative) and not from Dodaso, who is his father's relative.

Suggestion #2: Perhaps it is better to learn from Dodaso, since this also comes through Kidushin, and not from Achoso!

Answer: We include a maternal brother from "Ervas Achicha Hi" (the end of the verse; it is extra).

Question: Perhaps only a paternal brother's wife is forbidden, and the extra verse is needed to teach, when he has children, she is forbidden in the life of his brother and after his death!

Answer: If he has children, we already know that she is forbidden after he dies. Since the Torah permits Yibum when he has no children, we infer that when he has children, she is forbidden!

Suggestion #1: Perhaps when he has no children, she is permitted to the Yavam and forbidden to all others. When he has children, she is permitted to all!

Suggestion #2: Perhaps when he has no children, Yibum is a Mitzvah. When he has children, it is optional!

Suggestion #3: Perhaps when he has no children, Yibum is permitted. When he has children, it is forbidden, and the Isur is derived from a Mitzvas Aseh and is only a Chayavei Aseh!

Rejection: "Ervas Achiv Gilah (Aririm Yihyu)" (this is extra to teach about after the brother died. Aririm (having no children) alludes to Kares.)

Suggestion: Perhaps a maternal brother's wife is like a paternal brother's wife, and is permitted after death!

Rejection: "She is" - she remains forbidden.

Question: Why did the Torah mention Kares regarding a sister (all Arayos are Chayavei Kerisos)?

Answer #1: This teaches R. Yochanan's law:

(R. Yochanan): If one had Bi'ah with all the Arayos b'Shogeg, he brings a Korban for each one.

Answer #2 (R. Yitzchak): Even though one is normally lashed for Chayavei Lavin, Kares was written regarding one's sister to teach that the punishment for Chayavei Kerisus is Kares and not lashes.

Question: From where does R. Yitzchak learn R. Yochanan's law?

Answer: "V'El Ishah b'Tum'as Nidasah", obligates for each woman.

Question: Why did the Torah write regarding Dodaso "They will be childless"?

Answer - Contradiction: It says "They will be childless", and it says "They will die childless"!

Answer (Rabah): If he has children (when he sinned), he will bury them; if he had no children, he will die childless.

It was needed to write both:

Had the Torah written only "They will be childless", one might have thought that children he had before sinning will die, but not children after the sin;

Had the Torah written only "They will die childless", one might have thought that he will not have children after the sin, but children born before the sin will not die!

Question: What is the source that Ha'ara'ah is considered like Bi'ah regarding Chayavei Lavin?

Answer: Regarding a Shifchah Charufah (a Kena'anis slave or half-slave designated to an Eved Ivri) it says "Shichvas Zera" (one is liable only for a full Bi'ah, which can lead to semen). This implies that other Chayavei Lavin are liable for Ha'ara'ah.

Question: Perhaps we should learn contrarily! Since the Torah revealed that Chayavei Kerisus are liable for Ha'ara'ah, Chayavei Lavin are liable only for full Bi'ah!

Answer (Rav Ashi): If so, the Torah would not have needed to teach that Shifchah Charufah is liable only for full Bi'ah.

Question: What is the source that Ha'ara'ah is like Bi'ah regarding Chayavei Lavin of Kehunah?

Answer: We learn from a Gezeirah Shavah "Kichah-Kichah".

Question: What is the source that Ha'ara'ah is considered like Bi'ah regarding Chayavei Aseh?

Answer: We learn from a Gezeirah Shavah "Bi'ah-Bi'ah".

Question: What is the source that a Yevamah who has Bi'ah with a stranger is liable for Ha'ara'ah?

Objection: Amora'im (49b) argue about whether this is Chayavei Lavin or Chayavei Aseh. In either case; we gave the source above!

Correction: Rather, how do we know Ha'ara'ah is like full Bi'ah to acquire a Yevamah?

Answer: We learn from a Gezeirah Shavah "Bi'ah-Bi'ah".

Question: How do we know that Ha'ara'ah is like Bi'ah to make Kidushin?

Answer: We learn from a Gezeirah Shavah, "Kichah-Kichah".

Question (Rava): The Torah writes "Shichvas Zera" regarding Shifchah Charufah, Eshes Ish, and Sotah. Why are all of these needed?

Answer - part 1: We taught about Shifchah above;

Answer #1 - part 2: Regarding Eshes Ish, it excludes Bi'ah with Ever Mes (without Kishuy).

Question: This is like the opinion that exempts Bi'as Arayos with Ever Mes. According to the opinion that Bi'ah with an Ever Mes is liable regarding Arayos, how can we answer?

Answer #2 - part 2: It excludes Bi'ah with a married woman who died;

One might have thought that since she is still considered 'She'er' after death, one is liable for her. The verse teaches that this is not so.

Answer - part 3: A Beraisa teaches why it says "Shichvas Zera" regarding a Sotah:

(Beraisa): "Shichvas Zera" excludes something else.

Question: What does this refer to?

Answer #1 (Rav Sheshes): It excludes one who warned his wife against Bi'ah Lo k'Darkah.

Objection (Rava): It says "Mishkevei Ishah" (plural, to include Lo k'Darkah)!

Answer #2 (Rava): It excludes warning against intimacy other than Bi'ah.

Objection (Abaye): Did the Torah really forbid [a wife to her husband due to] mere lewdness?!

Answer #3 (Abaye): It excludes warning against Neshikah (touching of the genitals).

Objection: This is like the opinion that Ha'ara'ah is entrance of the crown (of the Ever). According to the opinion that says that it is Neshikah, how can we answer?

Defense (of Answer #2): Really, it excludes warning against intimacy other than Bi'ah. One would have thought that everything depends on the whims of the husband, and he is insistent on this (so it is valid warning). The verse teaches that this is not so.

(Shmuel): Ha'ara'ah is Neshikah.

This is like one who puts his finger on his mouth. Perforce, it will make some indentation.

(Rabah bar bar Chanah citing R. Yochanan): The Torah is Mechayev for full Bi'ah with a Shifchah Charufah. This is entrance of the crown.

Question (Rav Sheshes - Beraisa): He is liable only for a Bi'ah of Miruk.

Suggestion: This is when he fully enters the Ever (Tosfos; Rashi - he empties the Ever of its semen)!

Answer: No, he fully enters the crown.

(Rav Dimi citing R. Yochanan): Ha'ara'ah is the entrance of the crown.

Talmidim: Rabah bar bar Chanah said otherwise in R. Yochanan's name!

Rav Dimi: Either he is a liar, or I am!

(Ravin, citing R. Yochanan): Ha'ara'ah is the entrance of the crown.

He certainly disagrees with Rabah bar bar Chanah.

Question: Must we say that he disagrees with Shmuel?

Answer: No. From Neshikah until entrance of the crown he calls Ha'ara'ah.

(Rav Shmuel bar Yehudah citing R. Yochanan): Ha'ara'ah is the entrance of the crown. Full Bi'ah is literally full Bi'ah. Less than this is only Neshikah, and one is exempt for this.

He disagrees with Shmuel.