In 1833 slavery was abolished in the British West Indian colonies. A labour system that had been in operation for two hundred years, ended. A campaign based on the concept of freedom came to fruition. The idea of freedom was central to enlightenment thought. Freedom of speech, freedom of religion, freedom of conscience, freedom of movement, a free press, free trade and free labour were all part of enlightenment ideology. The institution of slavery, which limited all freedoms, came under pressure in an enlightened environment. Unlike the ancients who believed there could not be a civilized society without slaves, enlightenment philosophers developed the view that slavery was antithetical to civilization.