Complex sentence: Gibbes was a member of the Barbadian Society for the Improvement of Plantership, and the 1789 autobiography of Olaudah Equiano contains a description of him as "the most worthy and humane gentleman".
Split into simpler sentences: Gibbes was a member of the Barbadian Society for the Improvement of Plantership. The 1789 autobiography written by Olaudah Equiano contains a positive description of him, as "the most worthy and humane gentleman".