This is a passage from Thomas Jefferson’s draft of the Declaration of Independence that the Continental Congress cut before issuing the document in its collective name. It’s part of the litany of horrible things the Declaration blames on George III:
he has waged cruel war against human nature itself, violating it’s most sacred rights of life and liberty in the persons of a distant people who never offended him, captivating and carrying them into slavery in another hemispere, or to incure miserable death in their transportation hither. this piratical warfare, the opprobium of infidel powers, is the warfare of the Christian king of Great Britain. determined to keep open a market where MEN should be bought and sold, he has prostituted his negative for suppressing every legislative attempt to prohibit or to restrain this execrable commerce: and that this assemblage of horrors might want no fact of distinguished die, he is now exciting those very people to rise in arms among us, and to purchase that liberty of which he had deprived them, by murdering the people upon whom he also obtruded them: thus paying off former crimes committed against the liberties of one people, with crimes which he urges them to commit against the lives of another.Jefferson, a little miffed at being edited, made private copies of his draft for friends and posterity. (Those drafts differ slightly one from another, so some transcripts might read a little differently. Note Jefferson’s characteristic omission of capital letters at the start of sentences and possessive “it’s.”)
Sometimes people interpret this passage as a condemnation of slavery, but really it condemns the slave trade: the removal of people from Africa to the Americas. Some colonial legislatures, including Virginia and Massachusetts, had passed laws prohibiting the import of more Africans, and the Crown had vetoed them (i.e., “he has prostituted his negative for suppressing every legislative attempt to prohibit or to restrain this execrable commerce”).
No North American colony had moved to end slavery itself, however. Jefferson, while complaining about the unnatural cruelty of slavery and blaming George III for somehow forcing slavery on him and other colonists, never campaigned to end slaveholding within America.
The Congress deleted this passage for two big reasons: many delegates supported the slave trade, and the complaint didn’t pass the laugh test. Already supporters of the royal government were pointing out how many American shouting for “liberty” were also slaveholders.
The only oblique reference to slavery to survive in the Declaration was the line “He has excited domestic insurrections amongst us…”