This concept revolutionized Jewish eschatology. According to Sefer HaTemunah, we are currently in the —the cycle of Gevurah (Severity/Judgment)—which explains the prevalence of war, exile, and strict religious law. The next cycle, Tiferet (Harmony/Beauty), will usher in a messianic era where the Torah will appear "all kindness."
Sefer HaTemunah is famous among historians of science (and debated by Jewish philosophers) for a passage that describes the world going through cosmic cycles of 7,000 years, repeating in a cycle of 49,000 years (seven "shemitot").