Details. Their absence can create an entirely different impression. Consider the case of St. Bathild.
As a young English girl, she was sent into slavery in France. Apparently she was a relative of the last pagan king of East Anglia. When a Christian named Sigeberht overthrew him with the help of the Franks, Bathild got packed off to the Frankish royal household as a slave. Bangley says that pirates took her, but don't believe it -- these were new rulers punishing a deposed dynasty.
She learned to run the household competently, and was apparently easy on the eyes, as well. Erchinoald, the Mayor of the Palace (think of Denethor) and her actual owner, was a widower and took a shine to her, but she ran away until he married again; apparently this was okay since she eventually returned and resumed her service. Then young Pepin II, one of those boy kings whose kingdom is really being run by his Mayor, caught sight of her. She was nineteen when they were married; he was at most sixteen, no younger than twelve.
She was a force in the kingdom, and here we come to my point about details. Bangley says, "Because of her own experience, she took an active part in suppressing the slave trade and worked to release those already captured." Catholic Encyclopedia says: "She abolished the disgraceful trade in Christian slaves, and firmly repressed simony among the clergy. She also led the way in founding charitable and religious institutions, such as hospitals and monasteries."
Plainly she's a good person and a rare woman for her times. She found herself in a good position through some ill luck, capitalized on it, and assisted all three of her sons in ruling the kingdom until she eventually retired to a convent and spent her last years in prayer. But the difference between suppressing the slave trade and abolishing the enslavement of Christians is considerable in our time. Details.