Kav ha-Yashar was known for uplifting the spirits of Jewish communities in Europe after the Chmelnitzki Massacres of 1648-1649.[2] First published in 1705 in Frankfurt am Main, it has appeared in over 80 editions in nearly every country with a Jewish community.[citation needed] Kaidanover also prepared a Yiddish version, which went through at least 10 editions.[3]
The work draws on "Yesod Yosef", a musar work infused with the Kabbalistic teachings of Isaac Luria, written by Kaidanover's teacher, Yosef Yoske of Dubno;
[5]Kav ha-Yashar constitutes "a deliberate effort to popularize Safedian Kabbalah by adopting a much more understandable style in Hebrew."[1] Relatedly, it reflects, to some extent, a Kabbalistic dualism, dividing all aspects of reality "according to their affinity" either with the divine or with impurity.[3]
