The first dissertation written by an African slave was The Agony of Asar: A Thesis on Slavery by the Former Slave, Jacobus Elisa Johannes Capitein, 1717–1747, published in 1742. It is also the first scholarly work by an African slave. Capitein’s master took him from Guinea to Holland in 1828 and freed him. After that, grants from the wealthy enabled him to receive an education at the University of Leiden. Capitein returned to Guinea as a missionary. His work refutes the authors of antiquity and shows that slavery violated the principles of natural freedom and equality. He also rebuts Aristotle’s doctrine of natural slavery.