We got on board the Steam Boat Lebanon, in the locks of the Canal around 12 o'clock. M.[sic] of the day we left, and reached St. Louis the next monday [sic] at 8. P.M. Nothing of interest happened during the passage, except the vexatious delays occasioned by the sand bars bethought interesting. By the way, a fine example was presented on board the boat for contemplating the effect of condition upon human happiness. A gentleman had purchased twelve negroes in different parts of Kentucky and was taking them to a farm in the South. They were chained six and six together. A small iron clevis was around the left wrist of each, and this fastened to the main chain by a shorter one at a convenient distance from, the others; so that the negroes were strung together precisely like so many fish upon a trot-line. In this condition they were being separated forever from the scenes of their childhood, their friends, their fathers and mothers, and brothers and sisters, and many of them from their wives and children, and going into perpetual slavery where the lash of the master is proverbially more ruthless and unrelenting than any other where[sic]; and yet amid all these distressing circumstances, as we would think them, they were the most cheerful and apparently happy creatures on board. One, whose offense for which he had been sold was an over-fondness for his wife, played the fiddle almost continually; and the others danced, sung, cracked jokes, and played various games with cards from day to day. How true it is that "God tempers the wind to the shorn lamb," or in other words, that He renders the worst of human conditions tolerable, while he permits the best, to be nothing better than tolerable.
Lincoln: The Biography of a Writer (kindle 2217)
Note that this excerpt is from a letter written 22 years before the 1863 Emancipation Proclamation.
That excerpt from Lincoln's 1841 letter reads hauntingly like the riverboat scene at the beginning of Uncle Tom's Cabin published ten years later in 1851 by Harriet Beecher Stowe.
Were Stowe and Lincoln channeling each other?