First printing of the Zohar, the fundamental work of the Kabbalah (Jewish esoteric and mystical teachings), authored by the Talmudic sage, Rabbi Shimon Bar Yochai.
Links: The Kabbalah
Av 20 is the yahrtzeit (anniversary of the passing) of the Lubavitcher Rebbe's father, Rabbi Levi Yitzchak Schneerson (1878-1944), in Alma Ata, Kazakhstan. Rabbi Levi Yitzchak was Chief Rabbi of Yekaterinoslav (currently Dnepropetrovsk), and was arrested and exiled to Kazakhstan by the Stalinist regime as a result of his work to preserve Jewish life in the Soviet Union.
Links:
A Brief Biography
Rebbetzin Chana Scneerson's biography, which includes her account of her husband's heroism, arrest and passing.
Sometimes the cloud would be upon the Tabernacle for a number of days, and by G-d's command they encamped, and by G-d's command they journeyed.
And sometimes the cloud would be there from evening until morning, and the cloud was lifted in the morning and they journeyed...Or two days, or a year, or a month...By G-d's command they would encamp, and by G-d's command they journeyed. (Numbers 9:20-23.)
At every stop along their journey, whether it was for a year or for one day, the Children of Israel set up the Tabernacle and made all their offerings. Because they knew that they had been brought to this place by a divine hand, and so there must be purpose in this place, here, now.
Which teaches that in every journey of your life you must be where you are.
It may seem that you are only passing through on your way to somewhere else—but in truth there is purpose, divine purpose, in wherever you are right now.
Listen, learn, heal, plant seeds and water them. Neither you nor this place must stay the same.