The more a soul was split, the more unstable the original soul became, which in turn destabilized the person's emotions. It could even generate negative emotions on its own, and the person's mental state would become abnormal as well.
Voldemort's frenzied, neurotic behavior in his later years was inextricably linked to this.
Yet Voldemort had acquired vast amounts of knowledge in the Hogwarts library, as well as Slytherin's inheritance concerning the Tower Chapters. This had given him unparalleled power.
Even so, there were still gaps in his knowledge.
And unfortunately, Horcruxes were one of them.
Although Voldemort had learned of the existence of Horcruxes through all sorts of dubious channels, then learned how to make them from Slughorn, he knew nothing of their drawbacks.
And although the Slytherin Inheritance he had acquired covered a vast range of subjects, it happened to contain nothing about Horcruxes.
Well, that was perfectly normal.
Salazar Slytherin had been one of the greatest wizards of his age, and an exceptionally learned one at that. He knew the drawbacks of Horcruxes, so naturally, he would not have included such things in what he left to his successor.
But although Voldemort's mother had been a witch and he carried Slytherin blood, he had never obtained the inherited texts of the Slytherin family. As a result, there were many things commonly known among wizarding families that he genuinely did not know.
For instance, when Sirius learned that Voldemort might have made six or seven Horcruxes, he had nearly laughed himself into a fit.
Voldemort was particular not only about the number, but also about the objects that housed his soul fragments.
Of the seven Horcruxes he had planned, six had been made: his own Diary, Hufflepuff's Cup, the Ravenclaw Diadem, the Slytherin Locket, the Gaunt family Ring, and