Why do we need to know that there are 39 melakhot? After all, there's a list! It's all about what happens in a time period of forgetting (he'eleim). Defining "shogeg" with regard to Shabbat (again). Also: understanding the korban chatat. Plus: The case of the person who loses track of time and doesn't know what day is Shabbat. Do we resolve that in accord with God's count of 7 days or the human experience of Shabbat? Also, what does it mean to start keeping Shabbat again out there in the wilderness (if that's where you lost track of time)? The significance of Kiddush and Havdalah and the nature of Shabbat in our experience of the day (when keeping the melakhot is not the overwhelming experience of the day).