Yahrtzeit of Rabbi Tzvi Hirsch Kaidonover (1646-1712), author of the ethical work, Kav HaYashar ("The Just Measure"). As a boy, during the war between Sweden and Poland, he fled with his family to a village near Lublin. Two years later they were attacked by Cossacks, and his two sisters were killed. Kav HaYashar posits that it is incumbent upon any person who has been saved from a crisis to either correct something in his life or initiate a good deed, so that people will be aware that he is expressing his gratitude to God. This idea, he says, applies to everyone, for who can say he has never been saved from a tragedy?