The Smallest Measure of Defilement and the Forgotten Source

"The carcass of a wild beast" - what does "unclean" teach? That one might think I have liability only for the whole carcass; from where do I include an olive's bulk of it? Scripture says "unclean." "The carcass of a domestic animal" - what does "unclean" teach? That one might think I have only the carcass itself; from where its horn, its hair, and what is joined to it? Scripture says "unclean." "The carcass of a creeping thing" - what does "unclean" teach? That one might think I have only its flesh; from where its blood, its hide, what is joined to it, and what is mixed with it? Scripture says "unclean." Rabbi Eliezer says: "a creeping thing, and it is hidden from him" - for the forgetting of the creeping thing he is liable, but he is not liable for the forgetting of the sanctuary. Rabbi Akiva says: "and it is hidden from him, and he is unclean" - for the forgetting of the impurity he is liable, but not for the forgetting of the sanctuary. Rabbi Yishmael says: "and it is hidden from him" is said twice, to make one liable for the forgetting of the impurity and for the forgetting of the sanctuary. What is between them? Chizkiyah said: a creeping thing and a carcass are between them. Rabbi Eliezer holds we require that he know whether he was defiled by a creeping thing or by a carcass. Rabbi Akiva holds we do not require it: since he knows he was defiled, he needs no more. Ulla raised a contradiction between Rabbi Eliezer and himself: did Rabbi Eliezer say we require knowing whether he was defiled by a creeping thing or a carcass? Yet Rabbi Eliezer said: either way - if he ate forbidden fat he is liable, if leftover sacrifice he is liable, if he profaned the Sabbath he is liable, if Yom Kippur he is liable, if he lay with his menstruant wife he is liable, with his sister he is liable. Rabbi Yehoshua said to him: behold it says "his sin which he sinned" (Leviticus 4:23) - until you know wherein he sinned. The answer there: "which he sinned" the Merciful One said, meaning any sin at all; but here, since it is written "any unclean thing, or the carcass of an unclean creeping thing," why is it needed? Learn from it that we require he know whether he was defiled by a creeping thing or by a carcass. And Rabbi Akiva? Since the verse needed to write "domestic animal" and "wild beast" for Rabbi's teaching, it also wrote "creeping thing," as the school of Rabbi Yishmael taught: any passage that was stated and then repeated was repeated only for some new matter introduced in it. And Rabbi Eliezer - what does he do with this "in it"? It excludes one who acts without intent. Rabbi Yochanan said: there is a difference between them in the implications they draw. Rav Sheshet reverses Rabbi Eliezer for Rabbi Akiva and Rabbi Akiva for Rabbi Eliezer.