Without a fresh labour supply, the colony would be ruined. It was the office of the clergy to prove that this treatment of the natives was short-sighted and criminal, and their cause was taken up by the Dominican missionaries. In 1510 the preacher Montesino, taking for his text the words, "I am the voice of one crying in the wilderness," denounced the practice. Their mouthpiece with the Home Government, their immortal mouthpiece with posterity, is Las Casas, whose narrative is our authority. The government was anxious to preserve conquests that began to yield some profit. They appointed Commissions to advise, and followed sometimes one report, sometimes the other, taking generally the line of least resistance. The most important Commission of all, in which Las Casas asserted the duties of Christians and the rights of savages, against Sepulveda, who denied them, never came to a decision. Failing the native supply, the Spaniards substituted negroes. The slaves forwarded by Columbus had been sent back with tokens of the queen's displeasure, and Ximenes would not permit the importation of Africans. But the traffic went on, and the Indies were saved. Under Charles V 1000 slaves were allotted to each of the four islands. It did not seem an intolerable wrong to rescue men from the devil-worshippers who mangled their victims on the Niger or the Congo. Las Casas himself was one of those who advised that the negro should be brought to the relief of the Carib, and he would have allotted twelve slaves to each settler. He survived half a century, lived to lament his error, and declared his repentance to the world. He repented from motives of humanity rather than from principle; his feelings were more sensitive than his conscience, and he resembled the imperious Parliaments of George III which upheld the slave trade until imaginations were steeped in the horrors of the middle passage.