Theodore Dwight Weld (November 23, 1803 – February 3, 1895) was one of the architects of the American abolitionist movement during its formative years from 1830 to 1844, playing a role as writer, editor, speaker, and organizer. He is best known for his co-authorship of the authoritative compendium American Slavery as It Is: Testimony of a Thousand Witnesses, published in 1839. Harriet Beecher Stowe partly based Uncle Tom’s Cabin on Weld's text; the latter is regarded as second only to the former in its influence on the antislavery movement. Weld remained dedicated to the abolitionist movement until slavery was ended by the Thirteenth Amendment to the United States Constitution in 1865.
According to Lyman Beecher, the father of Harriet Beecher Stowe, Weld was "as eloquent as an angel, and as powerful as thunder." His words were "logic on fire".
In 1950, Weld was described as being "totally unknown to most Americans". His mother owned slaves. At age 14 Weld took over his father's hundred-acre (forty-hectare) farm near Hartford, Connecticut, to earn money to study at Phillips Academy in Andover, Massachusetts, attending from 1820 to 1822, when failing eyesight caused him to leave. After a doctor urged him to travel, he started an itinerant lecture series on mnemonics, traveling for three years throughout the United States, including the South, where he saw slavery first-hand. In 1825 Weld moved with his family to Fabius, in upstate New York. though he did not enroll as a student and does not appear in the College's published lists of students. About 1825 he stayed at the College in the suite of tutor William Kirkland, and not only attended classes but was "something of a leader among the students". He described himself as "educated at Hamilton College." However, Hamilton turned down his proposal of a manual labor program. he would spend two weeks at a time traveling about, lecturing on the virtues of manual labor, temperance, and moral reform. "Weld...had both the stamina and charisma to hold listeners spellbound for three hours." As a result, by 1831 he had become a "well known citizen" of Oneida County, according to a letter of Joseph Swan published in the Utica Elucidator.
Weld was described thus by James Fairchild, who knew him from when they were students together at Oberlin (of which Fairchild would later be President):
In an editorial comment in The Liberator, presumably by its editor Garrison, "Weld is destined to be one of the great men not of America merely, but of the world. His mind is full of strength, proportion, beauty, and majesty. ...[In his writing] there is indubitable evidence of intellectual grandeur and moral power."
In his reminiscences of that period Dr. Beecher observed: