- כלום מצינו טפל חמור מן העיקר (exceptions of מעשר שני, תמורה, and מותר פסח)
Ravina explained the source that שחיטה and קבלה of an עולה in צפון is מעכב: כלום מצינו טפל חמור מן העיקר – do we ever find the secondary [subject] more stringent than the primary [subject]? Since צפון is מעכב for חטאת, whose צפון requirement was only first derived from עולה, certainly it is מעכב for עולה itself. This assertion is questioned from maaser sheni, which itself may be redeemed, but לקוח בכסף מעשר – [food] purchased with maaser money cannot be redeemed (even if it becomes tamei, according to Rebbe Yehudah)!? The Gemara answers that here, לא אלימא קדושתיה למיתפס פדיוניה – its sanctity is not strong enough for its redemption to take effect (i.e., it is not a stringency of the secondary maaser, but a weakness). The Gemara asks further that although קדושת הגוף cannot take effect on a בעל מום, yet תמורה, whose kedushah is derived from the first animal’s kedushah, can take effect on a בעל מום!? It answers that a temurah’s kedushah comes from prior kedushah, in contrast to new kodashim, whose sanctity is attempting to take effect on chullin. Finally, the Gemara asks that מותר פסח – “remainder” of pesach (i.e., which was sacrificed after Pesach) requires סמיכה, נסכים, and waving the חזק ושוק, which an original pesach does not, but answers that a פסח during the rest of the year is actually a שלמים.
- דבר הלמד בהיקש אין חוזר ומלמד בהיקש
A היקש compares an אשם to both a חטאת and an עולה, and the Gemara asks why both are necessary, since either could have taught that an אשם must be shechted in צפון. Ravina explains that if the Torah would only compare אשם to חטאת, we would conclude that since the צפון requirement by חטאת itself is only derived from a היקש (to עולה), it must be that דבר הלמד בהיקש – something which learns its law through a hekesh חוזר ומלמד בהיקש – can in turn teach that law elsewhere through a hekesh. Comparing אשם to עולה as well avoids this conclusion. Ravina explained further that the Torah compared אשם to both, instead of only comparing it to עולה (the primary source of צפון), in order to teach that the היקש to חטאת could not have taught the צפון requirement, thereby demonstrating that דבר הלמד בהיקש שאינו חוזר ומלמד בהיקש – something which learns its law through a hekesh cannot in turn teach that law elsewhere through a hekesh. Rava provides another source for this rule.
- בכל התורה כולה למידין למד מלמד חוץ מן הקדשים
The Gemara proceeds to discuss which of the four types of derashos (hekesh, gezeirah shavah, kal vachomer, and בנין אב) can in turn teach its law elsewhere using another of those derashos (totaling sixteen combinations). The Gemara first asks if something derived from a היקש can be חוזר ומלמד בגזירה שוה. A proof is suggested from a Baraisa, which derives that פריחה בבגדים – spreading [of צרעת] over an entire garment is tahor from a gezeirah shavah (קרחת וגבחת) to אדם, whose own law of פריחה on ראשו – his scalp is derived from a היקש with his body. However, Rebbe Yochanan says: בכל התורה כולה למידין למד מלמד – throughout the entire Torah, we may derive a derivative from something which is itself a derivative (i.e., a two-step derashah), חוץ מן הקדשים שאין דנין למד מלמד – except regarding the subject of kodashim, where we cannot derive [a two-step derashah]. Rebbe Yochanan argues further that something derived from a היקש cannot be חוזר ומלמד בגיזרה שוה; otherwise, the Torah did not need to teach צפון by אשם, and we would have derived it from a גזירה שוה from חטאת, which was derived from עולה with a היקש.