This chapter confirms earlier speculations that horcruxes work by making backup copies of brain states (with the caveat that actually using the horcrux will merge its memories and personality with those of its host body, resulting in a hybrid entity). The theory that Harry James Potter-Evans-Verres is an instance of Tom Riddle (or, rather, a hybrid of Tom Riddle and the original Harry Potter) now seems very, very probable. It explains why Harry is as smart as Tom's other instances (the original Riddle/Monroe/Voldemort and the Quirrell/Riddle hybrid), and why the remember-ball glowed like the sun (Harry forgot Riddle's memories because he was too young to remember them).

I learned of the horcrux sspell ssince long ago.

Parseltongue has a word for "horcrux"?

Death iss not truly gainssaid. Real sself is losst, as you ssay. Not to my pressent tasste. Admit I conssidered it, long ago.

Voldemort used horcruxes, obviously (that's what the five hidden items in the elemental pattern are), but between the missing memories and the hybridization Quirrellmort doesn't consider them to be worth the trouble. Keep in mind that there is a nice theory about not being able to lie in parseltongue.

Not like certain people living in certain countries, who were, it was said, as human as anyone else; who were said to be sapient beings, worth more than any mere unicorn. But who nonetheless wouldn't be allowed to live in Muggle Britain. On that score, at least, no Muggle had the right to look a wizard in the eye. Magical Britain might discriminate against Muggleborns, but at least it allowed them inside so they could be spat upon in person.

I suppose open borders and unrestricted immigration are in-keeping with Harry's character as a utilitarian who tries to assign equal value to each and every human life.

Also, won't Quirrell die of transfiguration sickness if he drinks the blood of transfigured Rarity?