The Gemoro (61a, on the second mishna) says that there is a gezera of Biah Rishona because of Biah Shnia.
Why is Biah Shnia a problem?
We see from the previous mishna that being bo'el a lady who was previously an Almono is not in itself a problem, and after Biah Shnia she is his wife (so why is it worse than someone who was mekadesh an Almono, then appointed as Kohen Godol, who can do nisuin)!
(I'm probably missing something simple here!)
Meir Eliezer Bergman
Manchester UK
The previous Mishnah merely says that if a regular Kohen already did Eirusin with an Almanah, he may do Nisuin as well after he becomes Kohen Gadol due to a special Gezeiras ha'Kasuv. The end of the previous Mishnah explicitly states that even if a woman is a Shomeres Yavam and her brother-in-law is a Kohen Hedyot, who then is appointed after her husband dies to become the Kohen Gadol, he may not do Yibum. The Gemara explains that this case is excluded from the special Gezeiras ha'Kasuv. In other words, we do not see there is no problem for a Kohen Gadol to be with an Almanah. We only see an exception in the previous Mishnah in the specific and limited case where one already did Eirusin with a woman before becoming a Kohen Gadol. (The Ritva even asks that the second Mishnah doesn't even seem necessary once we have the first Mishnah.)
All the best,
Yaakov Montrose
To clarify my question:
Is it not also the case that if a regular Kohen was fully married to an Almanah, he may stay married to her after he becomes Kohen Godol.¦nbsp; Where do we know this from?¦nbsp; Is this same special Gezeiras ha'Kasuv also required for this case?
(I would then have thought that since after Yibum, the almonoh is his full wife, biah shniah should be the same as this case)
Meir Eliezer Bergman
Manchester UK
While I did not see anyone discuss this point, I would think that the Gezeiras ha'Kasuv is indeed needed for the case when they are already married. This Gezeiras ha'Kasuv is teaching us that he may "take his wife," meaning that he may only marry an Almanah who is deemed to be his wife. Kal v'Chomer he may stay with his wife! However, a Shomeres Yavam is clearly not as strong as a relationship as Erusin or Nisuin, and therefore is totally excluded from the Gezeiras ha'Kasuv without any Heter for Biah Shniah.
All the best,
Yaakov Montrose