I could not understand what the difference was between the fact that a necessary universal privative proposition is converted, and a contingent universal privative proposition is not converted. I thought that perhaps the answer would be revealed by asking figuring out why this was the case metaphysically. So, I went down the rabbit hole and tried to do an abstraction, and brought it to the tutor: “Why are universal privative propositions impossible? I reason that it is because even if A and B were not, the fact that they are, begins from somewhere, or some inductive universal predicate, or point of origin. E.g. every man is not every rock, and every rock is not every man, but both exist, and so therefore, they can’t mutually and indefinitely exclude the other into subversion.”
I overstepped myself, and the tutor tried to clarify and reel me back, while citing from Posterior Analytics, and later chapters in the Prior Analytics. I was not having any of that, so after a dialectical tennis match, I felt utterly lost, and that was not a good feeling. With a shattered brain the tutor finally brought me back to my original question, and demonstrated in a way in which clarity returned, and I could see again: “… the key difference between the conversion of necessary and contingent universal privative propositions lies in their logical necessity and how their conversion relates to syllogistic validity. First: “A is present with no B” being the necessary, and the second: “It happens that A is not present with any B” being the contingent.”
EAR