Horowitz was born on May 22, 1760, the day that the Baal Shem Tov died, to Menachem Mendel Rubin of Linsk.
As a youth, Horowitz studied in the yeshiva of his uncle Meshullam Egra, one of the Torah giants of the time, where his fellow students were Mordecai Benet and Yaakov Lorberbaum, who were to become two of the leading scholars of the next generation.
When Yosef Babad, the future author of the Minchas Chinuch, came to become a follower of his he sent him away, advising him to return home and pursue his studies in the revealed aspects of Torah.
Initially, Horowitz refused to give permission for the publication of his writings, but with the concurrence of his famous disciple, Chaim Halberstam of Sanz, author of Divrei Chaim, his two works, Zera Kodesh and Ayala Shelucha were finally published.
The only praise he permitted on his tombstone was "the singular one in his generation in the knowledge of God": ("יחיד בדורו בחכמת אלוקים".)