Rav Yoel Kahn [a Ponovitch graduate!] was the main "choizer" of the Lubavitcher Rebbe. He would listen to a 2-3-4-6 hour long talk on Shabbos and commit it to memory and then write it down on motzaei shabbos. [I can do that - but only during the week, with an mp3 player to record everything].
He told many stories of the Rebbe's genius in Torah. The Rebbe was always making siyumim [he was also up to date with everything happening in Israel, with the Mossad, in the Knesset, behind the Iron Curtain, in the White House, in New York, with his shlichim all over the world, in the personal lives of thousands and thousands of people etc. etc.]. In one of his Siyumei Hashas, he gave a talk about the machlokes between Beis Shammai and Beis Hillel throughout Shas as to whether we follow the בכח, the potential or we follow the בפועל, the actualized. Beis Shammai maintained that we follow the בכח while Beis Hillel contended that follow the בפועל. The Rebbe gave numerous examples. [See לאור ההלכה from Hagaon Rav Shlomo Yosef Zevin ztz"l for a detailed treatment of this topic].
1] The mishna in Uktzin [3/11] "חלות דבש מאמתי מיטמאות משום משקה, בית שמאי אומרים משיהרהר, בית הלל אומרים משירסק". If one wants to remove honey from the honeycombs, Beis Shammai says that the moment he has this thought the honey is considered a liquid and is susceptible to tumah. Beis Hillel says that we follow the בפועל, the actual removal of the honey. Until then there is no tumah.
2] More famously: Beis Shammai says that we light 8 candles the first night of Chanukah and 7 the next and descend from there. This is because בכח on the first night there are 8 days left. On the second there are 7 days left etc. etc. Beis Hillel says that we follow the בפועל and on the first night בפועל there is only one night of Chanukah. Hence, you light one candle. On the second night there are 2 candles because בפועל there are 2 days etc. etc.
The Rebbe brought numerous more examples. Some more straighforward while some required more explanation [I can send a copy of the sicha to those interested]. I was very bothered, related Rav Kahn. Why didn't the Rebbe mention an explicit Mishna "If a custodian intends [ but see Rashi] to misappropriate a deposit [שליחות יד], Beis Shammai says that he is liable for any mishap that might befall the deposit. Beis Hillel says that he doesn't assume liability until he actually misappropriates it [Bava Metzia 43b]".
Perfecto!! Beis Shammai says that you can take ownership and misappropriate an item with a thought alone - בכח. It is POTENTIALLY your property and you thus take responsibility. Beis Hillel says that you have to actually use it and thus perform a kinyan meshicha which makes it yours. Beis Hillel follows בפועל. In fact, Rav Yosef Engel [who is another personality whose originality and geshmakeit deserve 10,000 posts at least....] in his Beis Ha-otzar [1/27] cites this as an example of Beis Shammai and Beis Hillel לשיטתם about בכח against בפועל.
Rav Kahn could take it no more and asked after a few days wrote the Rebbe a note asking him why he skipped such an obvious example that would have strengthened his thesis. The Rebbe immediately wrote back and said that IT CAN'T BE that Beis Shammai holds that one can perform שליחות יד via בכח. He MUST perform משיכה and בכח doesn't fly. A kinyan is a kinyan.
He explained based on the Rogochover who writes "כלתה שמירתו, [ו]נעשה רשות הנפקד, והוי זה משיכה צורית". Meaning, when you give me an item to watch, the place where I put the item is considered rented to you. The moment I think that I am going to use the item for my own purposes [chas vi-shalom], I am halachically performing a משיכה on the place of the item and it is returned to my possession. This is called משיכה צורית. A kinyan in the world of צורה and thought. This kinyan meshicha is NOT בכח but בפועל. Thus, this would NOT be an example of an argument between Beis Shammai and Beis Hillel as to whether we follow the בכח or בפועל. [This fits well with our principle that Beis Shammai follows צורה while Beis Hillel says that halacha assigns value to what is done in the physical concrete world of chomer].
Geonus is knowing not only what to say but also what NOT to say....
לזכות נעכא גיטל בת רחל אסתר זרעא חיא וקיימא זרעא די לא יפסוק ודי לא יבטול מפתגמי אורייתא
P.S. The novelty of the words of the Rogochover is great and requires proof and a solid foundation. I leave that up to the Talmidei Chachomim, Korei Ha-blog....:-).
