Sojourner Truth never actually wrote any of her speeches. Having lived most of her life in slavery, Sojourner Truth was illiterate. She did receive some education from a Quaker family who took her in after New York, her home at the time, abolished slavery in the state.
Most of our versions of Sojourner Truth's speeches that we have recorded today were originally transcribed or copied down by someone who was in attendance and heard her speak. For example, her famous "Ain't I a Woman Speech?" was transcribed by Frances Dana Gage, who was the coordinator at the Women's Rights Convention.
Regardless of who wrote down her speeches, Sojourner's style was honest and rhetorically powerful. Her "Ain't I a Woman?" speech uses parallel phrasing, repetition, and cadence to drive her point home. She was a brilliant, natural speaker and an incredibly intelligent women despite the hardship of her humble beginnings.