In the “next world” a soul cannot grow spiritually, perform mitzvot or earn a better place. Basically, in the “next world” the soul reaps what it had sown in “this world.” However, a soul may gain merit through the deeds of its descendants.* During the festivals, the gates of heaven are already open to accept prayer, thus making it a perfect opportunity to add a special prayer for one’s deceased parent(s) or other family members. This service, known as Yizkor (“He shall remember”), is recited by Ashkenzim on Yom Kippur, Passover, Shavuot and Shemini Atzeret.
The Yizkor service is more than a prayer. On a personal level, it is an opportunity to reflect upon and remember the wonderful things that made the deceased person special. It is also a promise to act properly and give charity in the name of the deceased. (This is also why there are often synagogue fund-raising forms to be found attached to the Yizkor prayer--if people are pledging money, it is only proper for them to pledge support for the synagogue that provides for their religious needs.)
Yizkor may also be recited for other relatives (grandparents, aunts, uncles, etc.). In many communities it is also customary to recite a special prayer during Yizkor in memory of those who perished in the Holocaust and those who fell defending the State of Israel. In fact, many speculate that the memorial service originated as a result of the Crusades, when tens of thousands of Jews were murdered.
It is the custom among many Ashkenazi Jews that those whose parents are both still living leave the sanctuary during the service so as not to disturb the reflections and prayers of those who are reciting Yizkor.
*Descendants can also be non-biological--those one has taught or influenced in a significant manner.
This Treat is reposted in honor of Rosh Hashana.