His father, Samuel Jordan Harrison (1771–1846), was a well-to-do tobacco merchant, friend of Thomas Jefferson, who had helped to build the University of Virginia.
Failing to obtain an appointment as professor at the University of Virginia, in 1828 he traveled to Europe with a letter of introduction from Secretary of State Martin Van Buren.
He met Lafayette, Talleyrand, Benjamin Constant, Schlegel, and Goethe, and spent a year studying at the University of Göttingen.
Harrison delivered a series of literary addresses[2][3] and then, in the late 1820s, began publicly supporting anti-slavery thought.
Most importantly, he wrote a response to Thomas Roderick Dew's pro-slavery essay, Review of the Debates in the Virginia Legislature, 1831-2.