Dr. Slop is cursing Obadiah heartily. Because the bag of instruments jingled so that he couldn't hear himself whistle, Obadiah had tied the drawstrings of the bag into great knots. The knots are elaborate; furthermore, he has "tied and cross-tied them all fast together from one end" of the bag to the other. Tristram observes mournfully that if there had been a fair contest between his delivery from his mother and the delivery of the green bag from its knots — if both "she and Dr. Slop both fairly started together" — his mother would have won "at least by twenty knots," and his nose would have been saved. Dr. Slop was aware of that fact.
As Dr. Slop wrestles with the knots, he gets angrier and angrier. He cuts them with Walter's penknife, cutting his thumb at the same time. He curses Obadiah still more vigorously. Walter teases him about his great curses over such a small thing as a cut thumb, and when Dr. Slop says that no curse is too great, Walter hands him a ready-made curse to read, provided he reads it aloud. Dr. Slop, suspecting nothing, takes the curse, which turns out to be a form of "excommunication of the church of Rome . . . write by ERNULPHUS the bishop." Uncle Toby whistles "Lillabullero" as Dr. Slop begins. When he realizes what it is, he tries to get out of the reading. Walter holds him to his agreement, and Dr. Slop reads the powerful curse, inserting the name "Obadiah" at the proper points.
Tristram tells us his father's hypothesis that all modern curses and oaths derive from Ernulphus' anathema.
The chain of events working against Tristram has another couple of links forged for it in these chapters. Little things conspire against him, have always done so; little things of course conspire against every one of the Shandys, but sometimes they are at cross purposes. The knotting of Dr. Slop's bag — for the triviality of allowing Obadiah to hear himself whistle — worked against Walter's and Dr. Slop's plan for having the forceps handy for the delivery to protect the child's brain. And the cutting of the knots, freeing the forceps and making them available for the delivery, worked against Tristram's nose (as we shall see later). Everything seems to be dictated by pure chance, and yet everything goes uniformly wrong.
Walter's collection of esoteric literature serves him well for a change: when he baits Dr. Slop into using the Catholic excommunicatory curse, Dr. Slop is caught in his own trap.