First a word about bar Kamtza from Destruction of the Temple story as we leave Tisha b’Av. He was not just some guy who fell afoul of the party host – he was a malicious, self-hating Jew and extremely dangerous informer. Does that change the meaning of the story?
Chapter 22, Mishnas 3, 4
We may not create a new opening in a wine “barrel” (really a large clay jug), but we may lop off the top with a sword on Shabbos, as a show of generosity that we’re finishing the whole thing. Good news for me, because I like to saber the top off champagne bottles a la Napoleon’s cavalry officers! (How to video coming soon.) We may not, however, use a spear to poke a new hole in the clay barrel. We may insert an existing reed as a straw, but we may not cut a new reed. We may not use a myrtle leaf as a spout on Shabbos let we come to create an actual spout or cut a leaf from a tree, which would be a violation of “harvesting.” Rav would not sit on felt carried out by his young students via the device of wearing it as a cloak, but the reason was that he did not want to sit on felt while his colleague-disciples Rav Kahana and Rav Asi sat on the floor. If one’s cloak gets soaked while he’s walking on the road, he may wear it until he gets where he’s going. Previously the Sages ruled that he could then spread it out in the sun, as long as the public wasn’t watching, lest they think he’s “laundering on Shabbos.” Rav later reversed this ruling to hold like the minority opinions of Rabbis Elazar and Shimon in this mishna, establishing the key principle that actions which are prohibited due to appearance of impropriety in public remain prohibited even in private.