The more we learn about the story of Harry Potter, the more we will find that there are some subtle details hidden in it.
In particular, the author J.K. Rowling popped some small essays she wrote on the wizarding world website from time to time, allowing us to see more backstory outside of the main text novel.
Today, let's talk about the "cold knowledge" about this magical world.
Whether they are righteous wizards or evil wizards, they can learn the Patronus Spell.
For example, Umbridge, who everyone hates very much, uses the Patron saint spell to "fire pure fire".
But why don't dark wizards learn the Patronus Spell?
On the one hand, they don't have to learn. Dark wizards mostly don't need to summon the Guardian Spirits, as they would otherwise be unaffected by dark creatures.
On the other hand, dark wizards who use the Guardian Spirit Charm are mostly repulsed. It is mentioned in The Book of Magic: Book of Spells that once the Dark Wizards use this spell, most of them are devoured by maggots that spew out.
The nearly headless Nick explained in The Order of the Phoenix that when a wizard dies, he can choose to "go down" or "stay."
Almost headless, Nick chose to "stay" because of his fear of death, becoming a ghost who "did not collect in the underworld and not in the yang".
There is only one chance to choose this way, and once you become a ghost, it is "forever". Ghosts will never "die" a second time, even if they look at the Basilisk, they are only petrified.
Although, in a sense, the ghost has attained "immortality," such so-called "immortality" is limited. They must remain in a dead state forever and ever, without physical body, without physical contact, magic is limited to those that ghosts can make, and more importantly, their minds are always stuck in their lives, unable to learn new knowledge.
And all of the above was unbearable for Voldemort, so he would rather be trapped in the illusion forever than come back in a ghostly way.
Harry had hoped that his godfather Sirius would return to him in a ghostly manner, but the almost headless Nick's answer shattered his hopes.
In fact, wizards who still laugh at life before they die, or at the time of death, can never be ghosts, not only because they are not afraid of death, but also because they do not have any attachments or resentments in their hearts.
For example, Fred Weasley, who was brave, was still joking before he died, facing death calmly. A happy person like him would never become a ghost.
Muggle-born people, i.e., muggle wizards whose parents were both Muggles.
However, Muggle-born people who have little to do with wizards do not exist.
Magic is equivalent to a gene. At least one of the ancestors of the Muggle-born people must have been wizards, who passed on their magical genes to their descendants, but the descendants became carriers of this gene and did not show magical ability.
However, several generations later, when a magical heir reappears, he is considered a Muggle-born because of his lack of understanding of the ancestral wizarding background.
The potions of Hogwarts look similar to Muggle chemistry, except that the ingredients used are different.
I've seen someone ask the question, can Muggles become potions masters?
The answer, of course, is no. Because boiling potions also requires magic. Otherwise, why would wizards use their wands to stir the potions in the crucibles?
Wizards will use their wands to inject their magic into the potion, which is equivalent to a catalyst, causing a magical "chemical reaction" of various ingredients in the crucible.