And while we're at it, what was that book "x" recommended to counter it?
I found his intro most interesting. The triumphalism, the total disdain for moral objections that anyone might have to slavery (he calls it fanatical sentimentalism), the utter conviction that slavery is not a necessary evil but a positive good, the belief that the Founders were in error when they proclaimed all men to be equal.
I also thought his notions that capital can only be accumulated by essentially stealing (not the way he would put it) the excess value of the production of the slaves (or serfs) was very interesting. This is, of course, exactly what Marxism is based on, except that Kettel thought this theft was a good thing.
He has the odd idea that the American colonies before the Revolution were economically crushed by the boot of British finances. When of course we now know that the colonies in the early 1770s were thriving and growing economically, in fact had probably the highest median income on the planet, though with problems mostly created by inadequate money. But I guess that goes along with his notions that those who provide financing, shipping, insurance, etc. are by definition economically parasitical on farmers and planters.
Also, I appear to have been wrong about the date of publication being 1958. He references 1958 statistics throughout, probably because those were the latest available, but he also refers to John Brown’s attack on Harper’s Ferry, and the title page says 1860. So this is a pretty good representation of the thought of at least some southerners right before the election.
Stephen Colwell's The Five Cotton States and New York (1861). It's available at Google Books.
Kettell says that the Northern states are economically dependent on the Southern states. Colwell contents that the five Deep South states are very dependent on New York City economically.
Some have assumed that Colwell was also pro-slavery because his thesis pointed to the interdependence of the two regions, as Kettell's did, but I haven't found anything to support that.
You can find Kettell favorably reviewed in the secessionist DeBow's Review: