He found the sights of slavery offensive and when FitzRoy defended the practice by describing a visit to a slaveowner whose slaves replied "no" on being asked by their master if they wished to be freed, Darwin suggested that answers in such circumstances were worthless.
Encontrou que a visión da escravitude era ofensiva e cando FitzRoy defendeu esta práctica ao describir a visita a un propietario de escravos cuxos escravos responderon "non" ao preguntarlles o seu amo se querían ser libres, Darwin suxeriu que as respostas dadas en tales circunstancias non tiñan valor.