Beitza 36 a, b

Beitza 36a uses points from our last Mishna to flush out the differences in halachot on Festivals and on Shabbat.  Those points include clearing a room of stored produce for visitors, lowering drying fruits from the roof through a skylight, covering produce, wine and oil with cloths, placing a vessel beneath a leak.  They also look at beekeepers who cover beehives over the rainy months.  The bees are considered to be animals that are not 'meant' to be trapped.  

The rabbis continually consider how people will interpret their halachot.  It is assumed that people take the alachot of Shabbat seriously. But if the rabbis are lenient on Festivals, will Jews take those holidays with any seriousness at all?  Even though the Festivals are supposed to be less associated with obligation and more filled with joy, the rabbis do not trust that the community will be as stringent as necessary without their halachot.

Also of note is the reminder that monetary loss is thought to be less important that fulfilling mitzvot.  Especially if that monetary loss is 'minor'.

We are told a story about Abaye and his uncle, Rabba.  Abaye's millhouse's roof was leaking on Shabbat and he asked Rabba for direction.  Rabba instructed Abaye to move his bed into the millhouse and to consider the vessel catching the rainwater as the same vessel containing excrement or urine, which can be removed on Shabbat if it is repulsive.  Abaye thought about this, wondering if he should move something on Shabbat knowing that the move is not required.  While he was thinking, the roof fell in.  Abaye chastised himself for not following Rabba's advice immediately. 

This would not have stopped the roof from caving in, however.  

We learn that excrement or mice - things that are repulsive - can be removed directly (ie. by hand) if required.

Our next Mishna provides us with a list of activities that are prohibited by the Sages on Shabbat in the name of shevat, rest.  It also tells us which activities are 'optional'. Forbidden activities include climbing trees, riding animals, swimming, clapping, and dancing. Optional activities include judging, betrothing, performing chalitza, or performing a levirite marriage.  Although they are mitzvot, we are told not to consecrate, vow, consecrate objects to the priests, or separate teruma/tithes.  All of these acts are forbidden on Festivals and Shabbat; we are told that the only leniencies on Festivals regard food preparation.

Notes teach us that the rabbis expanded these suggestion, including marriage of any kind and divorce.

Why?
climbing a tree - we could break a branch which is like reaping
riding an animal - we could go beyond the eiruv and/or we could break a branch while riding [see above]
swimming - we could create a barrel as a floatation device
clapping - we could construct a musical instrument

Judging is discouraged though it is a full fledged mitzvah.  This is because there could be another qualified judge present, lessening the obligation to judge.

We will learn more about the other optional activities in tomorrow's daf.