Yahrtzeit of Rabbi Yitzhak Luria Ashkenazi (1534-1572), the father of modern Kabbalah, known popularly by the acronym, Arizal. He was born in Jerusalem, and later moved to Egypt where he studied under the great sages, Radvaz and Shita Mekubetzet. At age 22, he became engrossed in the study of the Zohar, and spent the next seven years in near-total seclusion and meditation. At age 36, he moved to Tzfat in northern Israel, where his colleagues included rabbis Yosef Karo (author of the Code of Jewish Law), the kabbalist Moshe Cordovero (Ramak), Shlomo Alkabetz and Moshe Alshich. Arizal taught extensively about reincarnation and transmigration of souls. His primary student, Chaim Vital, collected Arizal's lectures into a six-volume work entitled, Aitz Chaim (Tree of Life). Arizal died at age 38, and till today his tomb in Tzfat is a place of pilgrimage and prayer.

The 5th of Av is also the yahrtzeit of Rabbi Chaim Ozer Grodzensky (1863-1940), talmudic scholar and leader of eastern European Jewry. His father was a student of Rabbi Yisrael Salanter, the founder of the Mussar ethics movement. Rabbi Grodzensky was gifted with an infallible memory (he could recite complex texts word-for-word), and he testified that he never experienced "forgetting." In the years between the World Wars, he was the central rabbinic figure in Lithuania, at that time the world center of Torah scholarship. He authored a book of responsa, entitled Achi'ezer, drawn from the thousands of questions sent to him from all parts of the world.