Ever since Quirrell had used a dragon egg to trick Hagrid into revealing how to subdue Fluffy the three-headed dog, he had been in a foul mood, feeling like an utter fool who had been thoroughly played by someone else.
Though Quirrell had already found out about most of the magical obstacles, his spirits still refused to lift. From what he had gathered, most of the challenges were not actually difficult to get past once you knew the trick. However, Dumbledore had also placed magical protections around the Sorcerer's Stone itself, and that was the biggest obstacle of all. Moreover, when the time came to steal the stone, he would have to figure out a way to lure Dumbledore away to ensure he had enough time to break into the dungeon, steal the stone, and make his escape before Dumbledore returned.
Simply writing a letter to Dumbledore via the Ministry of Magic would not be nearly enough, because it would not take Dumbledore very long to travel from the Ministry back to Hogwarts.
Chapter 411