Theodore Parker (1810-1860) was an American transcendentalist minister and reformer known for his strong advocacy of social justice and abolitionism. He was a prominent figure in the Unitarian movement and played a significant role in the Transcendentalist literary and philosophical movement, which emphasized individual intuition and the inherent goodness of people. Parker was also a key figure in the fight against slavery, using his sermons and writings to promote the abolition of slavery in the United States. His famous quote, "The arc of the moral universe is long, but it bends toward justice," reflects his belief in progress and the eventual triumph of justice over oppression.