Random reflection on #ShavuotLive hour #9, Chava Shapiro's presentation "Pikuach Nefesh (Saving a Life) and the Moral Work of Jewish Law" was a very helpful presentation, digging into the history of the principle of Pikuach Nefesh (PK).
PK is interesting because it was pretty much a universal ethical principle (which overrode almost all mitzvot in importance) with little if any dissent, but also was a principle that is arguably post-Biblical.
I also appreciated Chava's response to my question about doing activism on #Shabbat.