Bava Kamma — Daf 66b

אומר לו הרי שלך לפניך והאי כיון דמטא עידן איסורא ודאי מייאש ואי ס"ד יאוש קנה אמאי אומר לו הרי שלך לפניך דמי מעליא בעי שלומי ליה

א"ל כי קאמינא אנא זה מתייאש וזה רוצה לקנות האי זה מתייאש וזה אינו רוצה לקנות

איתיבי' אביי לרבה (ויקרא א, ג) קרבנו ולא הגזול היכי דמי אילימא לפני יאוש למה לי קרא פשיטא

אלא לאו לאחר יאוש ש"מ יאוש לא קני

אמר ליה רבא וליטעמיך הא דתניא (ויקרא טו, ה) משכבו ולא הגזול

ה"ד אילימא דגזל עמרא ועבדיה משכב מי איכא למ"ד שינוי מעשה לא קני אלא מאי אית לך למימר דגזל משכב דחבריה ה"נ דגזל קרבן דחבריה:

איתיביה אביי לרב יוסף עורות של בעל הבית מחשבה מטמאתן

ושל עבדן אין מחשבה מטמאתן

של גנב מחשבה מטמאתן של גזלן אין מחשבה מטמאתן

רבי שמעון אומר חילוף הדברים של גזלן מחשבה מטמאתן ושל גנב אין מחשבה מטמאתן לפי שלא נתייאשו הבעלים

וש"מ יאוש קנה א"ל הכא במאי עסקינן כגון שקיצען

מתקיף לה רבה בר רב חנן והלא עיצבא שנו כאן ועיצבא אין צריכה קיצוע

דתנן כל מקום שאין חסרון מלאכה מחשבה מטמאתו יש חסרון מלאכה אין מחשבה מטמאתו חוץ מן העיצבא

אלא אמר רבא האי מילתא קשי בה רבה לרב יוסף עשרין ותרתין שנין ולא איפרקה עד דיתיב רב יוסף ברישא ופרקה שינוי השם כשינוי מעשה דמי

שינוי מעשה מאי טעמא התם מעיקרא עצים השתא כלים שינוי השם נמי מעיקרא קרו ליה משכא והשתא אברזין

והרי מריש דאיכא שינוי השם דמעיקרא כשורא והשתא טללא ותנן על המריש הגזול שבנאו בבירה שנוטל דמיו מפני תקנת השבים

טעמא מפני תקנת השבים

he can say to the plaintiff, 'Here is your stuff before you.'  Now, as this plaintiff surely renounced his ownership when the time for prohibiting leavened food arrived,  if you assume that Renunciation transfers ownership, why should the thief be entitled to say, 'Here is your stuff before you', when he has a duty upon him to pay the proper value?  — He replied:  I stated the ruling  only where the owner renounces ownership at the time when the thief is desirous of acquiring it, whereas in this case, though the owner renounced ownership, the thief had no desire to acquire it. Abaye objected to Rabbah's statement [from the following]: [The verse says,] 'His offering,  [implying] but not one which was misappropriated.'  Now, what were the circumstances? If we assume before Renunciation, why do I require a text, since this is quite obvious?  Should we therefore not assume after Renunciation, which would show that Renunciation does not transfer ownership?  Said Raba  to him: According to your reasoning [how are we to explain] that which was taught: [The verse says,] 'His bed  [implying] but not one which was misappropriated'? Under what circumstances? That, for instance, wool was misappropriated and made into a bed? But is there any [accepted] view  that a change [in substance] resulting from an act does not transfer ownership?  What you have to say is that it refers to a case where the robber misappropriated a neighbour's bed. So also here  it refers to a case where he misappropriated a neighbour's offering.  Abaye objected to R. Joseph's view [from the following]: In the case of skins belonging to a private owner, mere mental determination renders them capable of becoming [ritually] unclean  whereas in the case of those belonging to a tanner no mental determination  would render them capable of becoming unclean.  Regarding those in the possession of a 'thief', mental determination  will make them capable of becoming unclean,  whereas those in the possession of a 'robber' no mental determination  will render capable of becoming unclean.  R. Simeon says that the rulings are to be reversed: Regarding those in the possession of a 'robber', mental determination  will render them capable of becoming unclean,  whereas regarding those in the possession of a 'thief', no mental determination  will render them capable of becoming unclean, as in the last case the owners do not usually abandon hope of discovering who was the thief.  Does not this prove that Renunciation transfers ownership?  — He replied:  We are dealing here with a case where for example he had already trimmed the stolen skins [so that some change in substance was effected].  Rabbah son of R. Hanan demurred to this, saying: This was learnt here in connection with a [dining] cover,  and [skins intended to be used as] a cover do not require trimming as we have learnt:  Wherever there is no need for [finishing] work to be done, mental resolve  will render the article capable of becoming unclean, whereas where there is still need for [finishing] work to be done no mental resolve  will render it capable of becoming unclean, with the exception however, of a [dining] cover!  — Raba therefore said: This difficulty was pointed out by Rabbah to R. Joseph for twenty-two years  without his obtaining any answer. It was only when R. Joseph occupied the seat as Head  that he explained it [by suggesting that] a change in name is equivalent [in the eye of the law] to a change in substance; for just as a change in substance has an effect because, for instance, what was previously timber is now utensils, so also a change in name should have an effect as what was previously called skin is now called [dining] cover.  But what about a beam where there is similarly a change in name as previously it was called a post and now ceiling, and we have nevertheless learnt that 'where a misappropriated beam has been built into a house, the owner will recover only its value, so as to make matters easier for repentant robbers'.  The reason is, to make matters easier for repentant robbers,