Career
A leading figure in the early Hasidic movement, he became known as the chozeh, which means "secretary" or "visionary" in Hebrew, due to his great intuitive powers (he was actually nearly blind). He was a disciple of the Maggid of Mezritch. He continued his studies under Rabbi Shmelke of Nilkolsburg and Rabbi Elimelech of Lizhensk.
He lived for a while in Lantzut before moving to Lublin.
After Yaakov Yitzchak moved to Lublin, thousands of Hasidim flocked to learn from him. Among his disciples were such Hasidic luminaries as the Yid Hakodesh ("The Holy Jew"), Rabbi Simcha Bunim of Peshischa, Rabbi Meir of Apta, Rabbi David of Lelov, the Yismach Moshe, Rabbi Tzvi Elimelech of Dinov, Rabbi Naftali Zvi of Ropshitz, the Ma"or Vashemesh, and Sar Shalom of Belz.
During his stay in Lublin, Yaakov Yitzchak was opposed by a prominent rabbi, Rabbi Ezriel Horowitz. He was injured in a fall from a window on Simchat Torah, and died almost a year later on Tisha B"av from injuries relating to this fall.
He is buried at Old Jewish Cemetery, Lublin.