What compelled John Wesley to take up the cause of Abolitionism?

In 1778, John Wesley published his *Thoughts upon Slavery*, where he wrote: >The variety of ways that slavery appears make it almost impossible to convey a just notion of it ... First in what manner are they procured? Part of them by fraud ... But far more have been procured by force. The Christians landing upon their coasts, seized as many of them as they could find - men, women and children - and transported them to America ... It was some time before the Europeans found a more compendious way of procuring them: by prevailing upon them to make war in each other and sell their prisoners. Till then they seldom had any wars, all was peace and quiet. But the white man taught them drunkeness and avarice and hired them to sell one another. Nay, by this means even their kings are induced to sell their subjects ... As for the punishments that are inflicted upon them, say Sir Hans Sloan, some are gelded, others have half a foot chopped off ... others cut off an ear, and constrain them to broil and eat them ... > >How can Britons can so readily admit a change in their disposition and sentiments as to practise in America what they abhorred and detested in Britain can be accounted for no other principle than of being the natural effect of slave-keeping which as the celebrated Montesquieu observes 'insensibly accustoms those who are in the practise of it, to want all moral virtues, to become haughty, hasty, hard-hearted, passionate, voluptuous and cruel.' More, forty years earlier when he had been in the United States with his brother on missionary work in 1737-38 he recorded in his journal the barbaric treatment that: >daily practise upon their fellow creatures [inclufing whipping, driving nails through their ears and drawing teeth] ... even giving a white child a slave of his own to tyrannise ... [describing them] as shocking instances of diabolical cruelty Given the interest that Britain had in maintaining the slave trade it's not suprising to discover that whenever Wesley preached against the slavery trade he put his life at considerable risk. For example, when he preached in Bristol, one of the foremost slave-trading ports in Britain, a disturbance broke out. **Q. Given this, what compelled Wesley to take on slavery and become one of the early adopters of abolition?** **Moreover, given the shocking scenes of 'diabolical cruelty' he saw in the then slave owning United States why did it take so long to take up the cause?** **Finally, how significant was his preaching in the context of the abolitionist movement - my own understanding - from being told this at school - was that Wilberforce was the main force behind it**