Our position is thoroughly identified with the institution of slavery — the greatest material interest of the world. A blow at slavery is a blow at commerce and civilization. Utter subjugation awaits us in the Union, if we should consent longer to remain in it.
Original passage & context
"In the momentous step which our State has taken of dissolving its connection with the government of which we so long formed a part, it is but just that we should declare the prominent reasons which have induced our course. Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world. [...] a blow at slavery is a blow at commerce and civilization. [...] Utter subjugation awaits us in the Union, if we should consent longer to remain in it."
The first cascade state's manifesto — Mississippi seceded January 9, the day after South Carolina's window closes. Where South Carolina's declaration listed slavery among its grievances, Mississippi's makes it THE cause, in the first breath: an economy and a civilization staked on it. Non-contiguous sentences from the one document joined with [...]. Verified against the Yale Avalon Project. (Dated to the Jan 9 ordinance; the convention sat Jan 7–26.)
Read it in the original — Mississippi Declaration of Causes, Jan 1861 ↗