The common denominator of the non-priestly watches and the dates the wood offerings are brought is that they both are occasions when the Jewish people participate to a certain extent in the Temple service. Although the service itself is performed solely by priests, the entire people, or at least a representative group, symbolically join them in their ministering. In addition to the various details of the non-priestly watches and the wood offerings, the Gemara established that on any commemorative day, whether a fixed Festival from the Torah or a day on which hallel is recited, the prayers and fasting of the watches are diminished and the joy of the day is emphasized. Another topic that was addressed in this chapter was the fixed days of communal fasts. The Mishna and Gemara explained why these dates were chosen for the memorial fasts, and why they were established as permanent fast days. The main focus was on the Ninth of Av which, due to the numerous national disasters that occurred on this date, is not only established as a fixed communal fast, but is equal in severity to the extreme fasts for rain in that it begins at nightfall and requires all five categories of affliction to be observed. Certain practices of mourning are observed on the Ninth of Av. Essentially, all halakhot that apply to an individual mourner are obligatory for everyone on this day, as no actions that gladden the heart may be performed. Moreover, certain periods before the Ninth of Av, specifically the week in which it occurs and the previous eight days of the month, are included in various aspects of the mourning. The tractate ends on a positive note, as the Mishna mentions the celebratory atmosphere of Yom Kippur and of the fifteenth of Av, on which special festive events were staged for the entire nation with the aim of bringing the Jewish people together and increasing joy among them.