Secret archive ping!
The book's historical commentary said the letter was, in fact, a veiled ploy to convince Pope Pius to recognize the independence of the Confederacy and establish diplomatic relations; the pope did not do so.
The pope could have sent Davis a copy of his predecessor's encyclical: "In Supremo Apostalatus" Pope Gregory XVI (1839)
"We warn and adjure earnestly in the Lord faithful Christians of every condition that no one in the future dare to vex anyone, despoil him of his possessions, reduce to servitude, or lend aid and favour to those who give themselves up to these practices, or exercise that inhuman traffic by which the Blacks, as if they were not men but rather animals, having been brought into servitude, in no matter what way, are, without any distinction, in contempt of the rights of justice and humanity, bought, sold, and devoted sometimes to the hardest labour. Further, in the hope of gain, propositions of purchase being made to the first owners of the Blacks, dissensions and almost perpetual conflicts are aroused in these regions.
We reprove, then, by virtue of Our Apostolic Authority, all the practices above-mentioned as absolutely unworthy of the Christian name. By the same Authority We prohibit and strictly forbid any Ecclesiastic or lay person from presuming to defend as permissible this traffic in Blacks under no matter what pretext or excuse, or from publishing or teaching in any manner whatsoever, in public or privately, opinions contrary to what We have set forth in this Apostolic Letter."
The canon of the Bible was established in 398 AD, that’s when the books of the Bible was finalized after years of prayer. It would be nice if there were documents going back that far but those were turbulent times and understandably, many things did not survive.