The correct answer is William Wilberforce.
Wilberforce was a British politician during the late 18th and early 19th centuries. The quote above is referring to the slave trade. He says this quote as a way to show that individuals who are aware of the evils that come with the slave trade and know that it is happening can no longer claim ignorance. His writings helped inspire the Slave Trade Act of 1807, which made the slave trade illegal in Britain.