The Gemoro in Sanhedrin Daf 5b famously tells us that Rav lived on a farm for 18 months to get familiar with animals and more importantly Mumim to be able to Pasken Sheilos concerning Mum Oiver and Mum Kovuah.I like many others always wondered if there was a significance in this amount of time,18 months ia quite a specific period of time so was there any Kavono in Rav's actions or is it a case of Maaseh Shehoyoh Kach Hoyoh.
I recently was learning the Sugya in Bechoirois Daf 38b which brings a Halocho about being able to tell whether Mayim Kevuim is a Mum Oiver or a Mum Koiveah and brings a solution concerning feeding it even though it only seems to be a Shiur of a Groigeres Chotzir Lach and Chotzir Yovesh over a certain amount of time. I was wondering what the Kollel thought that based on the rulings there in the Gemoro and Rashi and the Rambam if you don't mind being Meayen in the Sugya and also the Reshash's question on the Gemoro I think that to cover all bases of whether the animal had to have Lach and Yovesh in the right season and in what order it must eat it Al Korchach Rav had to be around for 18 months to see the difference between Mum Oiver and Mum Koiveah, especially if you bear in mind what Rashi Al HaTorah tells us in Parshas Vayishlach that when Yaakov journeyed to Sukkos and we are told it was for 18 months it means 3 seasons Kayitz,Choref and Kayitz
Any thoughts,
Kol Tuv
Boruch Kahan, LONDON
Your theory is very interesting and thought-provoking. However even taking in the different opinions and even allowing for Lach after Yaveish and Yaveish after Lach and allowing for a full three months as per the Rashash's question, it isn't go to be requiring 18 months to learn. It would seem to me that there is a lot else to learn about Mum Oveir and Mum Kavua and this could take some time to verify and this is why he required 18 months.
As for Rashi in Vayishlach, he doesn't say it was less than 18 months but just proves the point from the need for Sukkos twice and a Bayis once. This means that Yaakov arrived around Pesach and stayed until the following Sukkos thus requiring twice Sukkos and once a Bayis.
Yoel Domb