Beitza 38 a, b

The rabbis continue their conversations about the halachot of Festivals.  They wish to identify how observance on Festivals can be distinguished from the halachot of weekdays and of Shabbat.  Some highlights from today's daf:

• Bereira: retroactive designation
• when facts were not established at a certain time but those facts were determined later, we ask questions about whether or not the act was understood retroactively
• Gilui Milta Lemafreya: retroactive discovery of a matter
• when facts are known at a certain time, but a person was not aware of those facts.  We can clarify the situation retroactively.
• As the feet of another: when another person has the power to determine either facts or decisions
• an ox fattener is as the feet of all people
• an ox of a shepherd is as the feet of the people in that city only
• when one borrows a vessel before a Festival; it is as the feet of the borrower
• when one borrows a vessel before a Festival but it is delivered on the Festival; it is as the feet of both the borrower and the lender
• when one borrows a vessel during a Festival; it is as the feet of the lender

The rabbis discuss the concept of nullification when foods are combined.

• When a prohibited item is combined with permitted items of the same type, it is nullified
• Salt and water may 'disappear' when they combine with wheat from dough
• Nullification and Monetary matters are compared with nullification of slaughtered and unlsaughtered meat, which is debated.
• The rabbis point out that spices added to a dish cannot be nullified as even small amounts change the taste of the dish