I wondered how JA would ever know of the Abbe Raynald's works....well, she could have found out via Mr Clarkson, who talks of this book :
The second was the abbé Raynal. This author gave an account of the laws, government, and religion of Africa, of the produce of it, of the manners of its inhabitants, of the trade in slaves, of the manner of procuring these, with several other particulars relating to the subject. And at the end of his account, fearing lest the good advice he had given for making the condition of the slaves more comfortable should be construed into an approbation of such a traffic, he employed several pages in showing its utter inconsistency with sound policy, justice, reason, humanity, and religion.
“I will not here,” says he, “so far debase myself as to enlarge the ignominious list of those writers, who devote their abilities to justify by policy what morality condemns. In an age where so many errors are boldly laid open, it would be unpardonable to conceal any truth that is interesting to humanity. If whatever I have hitherto advanced hath seemingly tended only to alleviate the burthen of slavery, the reason is, that it was first necessary to give some comfort to those unhappy beings, whom we cannot set free, and convince their oppressors, that they were cruel, to the prejudice of their real interests. But, in the mean time, till some considerable revolution shall make the evidence of this great truth felt, it may not be improper to pursue this subject further. I shall then first prove that there is no reason of state, which can authorize slavery. I shall not be afraid to cite to the tribunal of reason and justice those governments, which tolerate this cruelty, or which even are not ashamed to make it the basis of their power.”
And a little further on he observes—“Will it be said that he, who wants to make me a slave, does me no injury, but that he only makes use of his rights? Where are those rights? Who hath stamped upon them so sacred a character as to silence mine?”—
In the beginning of the next paragraph he speaks thus: “He, who supports the system of slavery, is the enemy of the whole human race. He divides it into two societies of legal assassins; the oppressors, and the oppressed. It is the same thing as proclaiming to the world, If you would preserve your life, instantly take away mine, for I want to have yours.”
Going on two pages further, we find these words: “But the Negros, they say, are a race born for slavery; their dispositions are narrow, treacherous, and wicked; they themselves allow the superiority of our understandings, and almost acknowledge the justice of our authority.—Yes—The minds of the Negros are contracted, because slavery destroys all the springs of the soul. They are wicked, but not equally so with you. They are treacherous, because they are under no obligation to speak truth to their tyrants. They acknowledge the superiority of our understanding, because we have abused their ignorance. They allow the justice of our authority, because we have abused their weakness.”
“But these Negros, it is further urged, were born slaves. Barbarians! will you persuade me, that a man can be the property of a sovereign, a son the property of a father, a wife the property of a husband, a domestic the property of a master, a Negro the property of a planter?”
But I have no time to follow this animated author, even by short extracts, through the varied strains of eloquence which he displays upon this occasion. I can only say, that his labours entitle him to a high station among the benefactors to the African race.
Thomas Clarkson, The History of the Abolition of the African Slave-Trade, vol. 1 
It might be too tenuous a link, but I'm just "putting this out there" for consideration, as it were ;-)