"What is the Slave Trade, and what is the cause of it? People do not make slaves through love of cruelty or mischief, but they do so because they made their livelihood by it. Tribes are enslaved, are taken as slaves, in order to carry burdens to the coast, and when they have done that they are sold for what they will fetch. If you could give to the slave-raiding Arabs, who at the present moment are the most barbarous and brutal people on the face of the earth, peaceful means of making an honest livelihood, do you mean to say that they enjoy war so much that they will not accept these means? If you say so, I think all history and experience is against you. You have never found a case where it has been made profitable to a nation or tribe to keep the peace that they have not done so... Make it the interest of the Arab slave traders to give up the Slave Trade, and you will see the end of that traffic."
January 1, 1970
https://en.wikiquote.org/wiki/Joseph_Chamberlain