The science and laws of the right of secession was taught by certain fire-eaters at some Southern Universities in the early years of the 1800s. It was their goal to see that someday it would happen. The biographies of some of the first fire-eaters are very interesting and revealing on their motives for disunion. The Union for them was always unnatural. They felt that the States south of the Mason-Dixon would be happier as their own Union excluding the culturally different North. Agreed, without slavery, their motives for secession would not have found an interesting ear in any majority of Southerners. However, they were the drum beaters that Southerners listened too, and they convinced one portion of the South that the crisis to protect slavery was enough for disunion. There are writings on the meetings of well known abolitionist politicians meeting with fire-eaters in Charleston, as friends and gentlemen, they had, it is said, mutual goals.
On another point, after John Brown's raid, some of those Southerners who had no interest in slavery, who had been unionist were now willing to secede to protect themselves from the effects of slavery; abolitionist laws, abolitionist attacks and insurrection plots. It’s a complicated growth of how secession took over the minds of many Southerners and may never be understood, it is certainly not clear secession was for the sake of protecting the slave owners right to own slaves and was the primary moral cause.