“The philosophical doctrines consulted for the Declaration of Independence and Constitution placed master and slave on the same plain of existence . . .”
That is an interesting comment.
When Jefferson wrote about “merciless Indian Savages” was that too for the purpose of placing native Americans on the same “plain” of existence?
The reason I ask: I don’t think Jefferson was advocating making college presidents, electors, or jurists of native Americans when he wrote the DOI.
I would be surprised if you can find primary sources to argue he was.
Practical application of these primary theoretical sources to circumstances often requires a good deal of energy. I think of the persistence of William Wilberforce which caused the most ordinary men of Great Britain to find positions needed to abolish slavery throughout the Empire in 1833. He first had to convince his colleagues these things were humans deserving application of political theory to them.