Wikipedia
Kotsk (Hasidic dynasty)
''' Kotsk ''' (Kotzk) is the name of a Hasidic dynasty founded by Rebbe Menachem Mendel Morgenstern, known as the Kotzker Rebbe.
Kotsk is the Yiddish name of Kock, a town in present-day Poland.
The first Rebbe of Ger, Rabbi Yitzchak Meir Alter, known for his work as the Chidushei Harim, was a preeminent disciple of the Kotzker Rebbe. Following the Kotzker's death most of the Kotzker Hasidim formed the nucleus of the Ger dynasty.
The Kotzker Hasidim were known for their critical thinking and for a controversial way of expressing themselves.