Bekhorot 32: Revisiting Gezarah Shavah

A discussion here compares the first-born with tithed animals. For a firstborn, it cannot be redeemed, but it can be sold. And tithed animals are the reverse. What's the source? The Gemara explains that for the subjects of this group much be free. Thus, there are two steps here - establishing that a "maaser" item cannot be redeemed to begin. with. The details, for those who delve in, show many different appearances of non-Geulah. Also, a focus on the "gezarah shavah" as the methodological leading principle here. The phrase cannot be used for other inferences for that gezarah shavah to work at all. Also, a statement by Rava about how that which has been dedicated cannot be redeemed, at least when it's a first-born animal. Plus, it depends where the items are - whether in the kohen's possession or that of the owner. Also, a very small new mishnah (!), with a dispute between Beit Shammai and Beit Hillel, as to whether those partaking of a blemished first born could sit together -- B"Sh says only kohanim; B"H says even a non-Jew!