Based on a Naaleh.com shiur by Rabbi Avishai David
The Gemara at the end of Taanit cites a famous braita which says that all the mitzvot that are relevant to a mourner are relevant to Tisha B’av. The Rishonim point out this is not always absolute.
The Gemara discusses an custom of aveilut (mourning) which used to be practiced by a mourner. This practice is called kfiyat ha’mitah (turning over the bed). Rav Yehuda maintains that this practice applies to Tisha B’av. The Chachamim disagree. The Rosh adds another custom no longer practiced today, atirat harosh, swathing the head. He notes that the chachamim disagree with Rav Yehuda about the first practice and this one too. The Rosh then questions how we can understand the braita. He answers that it only relates to negative commandments. Positive practices that devolve upon an avel do not apply to Tisha B’av.
An avel must tear his garmentbut on Tisha B’av there is no such practice. The Gemara indicates that kriah is only warranted when a person is in a passionate emotionally heightened state such as when he experiences a moment of great loss. It is also applicable when a person hears bad news. Tisha B’av is lacking both of these aspects. Therefore, we do not tear kriah.
The Rosh writes that although an avel doesn’t don tefillin, on Tisha B’av we are obligated to do so. This is because the prohibition of wearing tefillin for a mourner is only on the first day of aveilut. Tisha B’av isn’t compared to the first day. The Rosh writes that an avel may not work as it is considered hesech hada’at, a diversion. But on Tisha B’av it is permitted to do work b’makom shenhagu (in a place where it is the custom). Similarly, the Rosh notes that an avel is prohibited from engaging in sheilat shalom (salutary dialogue). Yet on Tisha B’av one may respond to a greeting (although this is not our practice). An avel may not become engaged to be married. Yet the Rishonim permitted a person to become engaged on Tisha B’av lest someone take his zivug (predestined mate) before him.
There is a distinction between the nature of the prohibition of studying Torah for an avel and on Tisha B’av. The prohibition for an avel is derived from a verse in Yechezkel, where the Navi says the avel should be silent. However, on Tisha B’av the prohibition stems from the verse, “Pikudei Hashem yesharim mesamchei lev.” Learning Torah brings joy and on Tisha B’av this kind of happiness is not permitted. Studying the tragedies of the churban does not engender such joy. Therefore, we may study these subjects.
The Gemara notes a difference between aveilut chadasha (fresh mourning), when a person loses a close relative, as opposed to aveilut yeshana (historical mourning) which is related to Tisha B’av. Aveilut chadasha evokes within a person powerful emotions of grief. Aveilut yeshana, which happened so long ago, is more difficult to arouse.
A Jew is obligated to surrender to the will of Hashem. This should not prevent our natural emotions from emerging. The customs of individual aveilut were designed so the mourner would be able to express his emotions in a wholesome way. At the beginning, a mourner is not in a rational state of mind. Gradually he disengages himself from his emotions. Halacha recognizes this and proscribes four periods of mourning. Each stage engenders specific laws relative to the mourners diminishing emotions.
The halacha doesn’t demand of us to plunge into aveilut. Mourning begins in Tamuz. The Mishna writes “Mishenichnat Av mima’atim b’simcha.” The feeling of mourning gradually increases. Although we’ve gone through hundreds of Tisha B’av’s our relationship to the past is a living reality. For us the past is integrated into the present, which anticipates the future. They all combine into one continuum of tradition passed down from generation to generation.
With the beginning of the nine days before Tisha B’av, Chazal introduced restrictions to prevent hesech hadat. Whatever will cause diversion is prohibited. With aveilut chadasha one’s emotions are so powerful that one is completely enveloped in mourning. However, with aveilut yeshana, any distraction can automatically divert us. Therefore, chazal introduced extra restraints to keep us focused.