Ethan thought the teacher's idea was a bit problematic, but a good student shouldn't embarrass their teacher. Seeing Lindong's face nearly reddening to her neck, he decisively skipped over the topic.
Ethan: "Three hours is enough, but in a place where forbidden books are stored, there should be other restraints, right?"
Invisible potions aren't expensive in the black market. If a bottle of medium-level magic potion can easily access all kinds of forbidden books, the world's mystical knowledge would have long been rampant.
The content in forbidden books is far more valuable than magic potions, and he knows that many people, like Lindong, have a penchant for them — the more others forbid them from looking, the more they want to see.
If the same content were written in ordinary books, placed where it could be easily accessed, they'd lose interest instantly.
"Of course, breaking the restraints is a necessary part of sneaking forbidden books."