What are the implications of "Vera'isa ba'Shivyah"?
Kidushin, 21b: It implies that he desired her when taking her captive, but not if he took her captive in order to sell her or as a slave and the desire for her came upon him only later.
Oznayim la'Torah: It hints at what Chazal have said 'Lo Dibrah Torah Ela Keneged Yeitzer ha'Ra', based on what they also said - in Sotah, 8 - 'Ein Yeitzer has'Ra Sholet Ela ba'Meh she'Einav Ro'os', and that the Yeitzer ha'Ra, who is alias the Satan and the Mal'ach ha'Maves, is full of eyes. 1
See Oznayim la'Torah, who elaborates. See also Rashi on the Pasuk "ve'Lo Sasuru Acharei Levavchem ve'Acharei Eineichem" - Sh'lach l'cha, 15:39.
On what grounds does the Torah permit marrying a Y'fas To'ar?
Rashi: In order to counter the Yeitzer-ha'Ra, 1 which would otherwise talk him into marrying her be'Isur 2 (and the Torah only permits her immediately where the captor cannot wait for the process to finish - Riva).
Sotah, 35b: It can be compared to someone who needs to eat an animal that is sickly (and is therefore unhealthy) and which it is preferable to eat when it has been Shechted 3 than as a Neveilah 4 - and it is in that vein that the Torah permits a Y'fas To'ar.
See Sifsei Chachamim and Ba'al ha'Turim. Meshech Chochmah (in No'ach Bereishis, 9:7): The Torah does not demand more from people than what they are capable of doing. It permitted a Y'fas To'ar, because in time of war, the Yeitzer ha'Ra is too powerful - but under normal circumstances, the Torah expects us to overcome the Yeitzer ha'Ra.
When at least it is permitted.
See Torah Temimah, note 72 and Ba'al ha'Turim on the word "Eishes".
Since when does the Torah permit an Isur out of concern that one may otherwise commit a sin?
Oznayim la'Torah: It is only here, where the men, Tzadikim 1 who are already under tremendous strain and whose wives are not with them, are being lured by the enemy women to the point that they are Anusim, that the Torah permits it in order to prevent them from one sin to another and end up sinning on purpose.
See Oznayim la'Torah DH 'Valakachta l'cha le'Ishah', who elaborates in detail.
Why does the Torah insert the word "Eishes Y'fas To'ar" instead of 'Ishah ? '?
Rashi: To permit her even if she is married. 1
See Torah Temimah, note 71 and Sifsei Chachamim, who elaborates.
What if she is not beautiful?
Ramban (citing the Sifri): Beauty is not crucial to a Y'fas To'ar 1 - and the Torah mentions it only because a man is generally attracted to a (strange) woman due to her beauty.
Why does the Torah insert the words "Vechashakta bah"?
Ramban (citing the Sifri): To teach us a. that the Heter is based on his desire for her, and that, consequently, she is permitted to him even if she is not beautiful 1 and b. that he is only permitted if he actually has a desire to be intimate with her, but not if he merely wants a wife.
Kidushin, 22a: It implies that he is only permitted to take one Y'fas To'ar, but not two. 2
Oznayim la'Torah: Refer to 21:11:0.1:2 and note. This is the next stage of the Yeitzer ha'Ra, 'The eye sees and the heart desires' - a recipe for disaster, as Chazal stated in Avos, 5:16 'Kol Ahavah she'hi Teluyah be'Davar ... '. 3
What are the connotations of "Vehaysah l'cha le'Ishah"?
Rashi: Refer to 21:13:5:2*.
Ramban (citing Kidushin, 21b and the Sifri): It means that the first Bi'ah is permitted immediately. 1
Riva: It implies that he intends to take her as a wife 2 (and not as a slave and then changes his mind). 3
Sifri: It teaches us that he is obligated to give her She'er, K'sus ve'Onah. 4
Kidushin, 22a: It teaches us that the Kidushin takes effect - and that his children are therefore Jewish. 5
Refer to 21:13:5:1*.
Later in Pasuk 13, when the Torah writes "u'Ve'altah ve'Haysah l'cha le'Ishah", it implies that before that, she was not his wife.
Refer to 25:11:0.1:1.
See Mishpatim Sh'mos, 21:10 and Torah Temimah, note 70.
See Torah Temimah, note 89.
Why does the Torah add the word "Ve'lakachta l'cha le'Ishah"?
Ramban #1 (citing the Sifri): To prohibit taking her as a wife for his father or his brother.
Ramban #2 (citing Kidushin, 22): To prohibit taking two women, one for himself and one for his father or his brother. 1
See Ramban and Torah Temimah, note 76.
Why does the Torah write "Y'fas To'ar" and not 'Y'fas Mar'eh'?
Rosh: They were under siege, and due to hunger, their faces change [detrimentally]. It says Y'fas To'ar, for she is fitting to receive the beauty 1 that was lost in the days of hunger.
Even though in Vayeitzei Bereishis, 29:17 regarding Rachel, the Rosh translated "Y'fas To'ar" as tall in stature, it seems that here he holds like Rashi and Rashbam (Ibid.), that it refers to the shape of the face, and Y'fas Mar'eh is the complexion. The Sifri says that Ke'urah (ugly) is not Y'fas To'ar. (PF)
QUESTIONS ON RASHI
Rashi writes that "Eishes" permits a Y'fas To'ar even if she is married. "Eishes Re'ehu" already excludes [from the Isur] a Nochri's wife?
Riva (citing R. Elyakim, from Sanhedrin 57a): If not for the D'rashah here, it would be forbidden due to theft (taking another man's wife 1 ), but not due to Arayos.
Riva: The D'rashah here is indeed based on the word "Eishes" in "Eishes Re'ehu".
Riva: Some say that the D'rashah of Eishes Re'ehu excludes only Misah, but the La'av remains. And here, the Torah totally permitted it. 2
Riva citing R. Tam, Moshav Zekenim: If not for the current Pasuk, we would have thought that there is an Isur Asei of "ve'Davak be'Ishto" (Bereishis 2:24) - to cleave to one's own wife and not to somebody else's. The Pasuk therefore teaches us that there is not even an Isur Asei.
If we may kill her husband in war, how can it be forbidden to take his property?! Perhaps the Heter is needed for a captive whose husband is from a nation not involved in the war (PF).
Riva: This is wrong. The Chachamim decreed NaShGaZ (one who has relations with a Nochris, it is as if he had relations with a Nidah, Shifchah, Goyah and Zonah (Avodah Zarah 36b. It seems that the text should say NaShGA, like the opinion there that includes Eishes Ish ? PF). This implies that the Isur is only mi'de'Rabanan. If so, no Pasuk is needed!
Rashi writes that the Torah permits her in order to counter the Yeitzer-ha'Ra. But in Kidushin (22a), Rashi writes that intimacy is forbidden until after the entire Parshah (including a month of mourning?)?
Moshav Zekenim #1 (citing R. Tam): The first Bi'ah is permitted immediately. The Gemara forbids a second Bi'ah before all the actions have been completed. 1
Moshav Zekenim #2: Because once he knows that she will be permitted afterwards, the Yeitzer ha'Ra for her subsides (and he can control himself until she is permitted).
Refer to 21:12:151:1.