Fortunately, not long after classes officially began, Harry and his friends attended their first Defence Against the Dark Arts lesson of their fourth year.
Sherlock's classes were always highly anticipated, as his teaching methods differed for each year group.
Before the lesson began, the students were still discussing the Triwizard Tournament.
There was still more than a month before the competition officially started, but the students were already impatient, wishing time would speed up and October would arrive sooner.
When Sherlock walked into the classroom, he immediately sensed the students' restlessness.
It wasn't just the fourth-years; the other young wizards were in the same state. The Triwizard Tournament had brought a new sense of excitement to Hogwarts this year, making the students, whose attitudes towards studying were already far from serious, even more distracted.
"First of all, the competition hasn't officially started yet, and you're all fourth-year students. Not a single one of you is over sixteen, so don't entertain any illusions about participating in the competition."
Before the lesson had even begun, Sherlock had already poured a bucket of cold water over their enthusiasm.
"I don't know whom Dumbledore has invited to serve as judges, but even if you picked an idiot at random off the street, they'd recognise that a fourth-year student couldn't possibly be seventeen. And Dumbledore certainly wouldn't appoint an idiot. So you'd better keep your feet on the ground. Fourth-years won't have the opportunity to participate. This year, be content with watching from the sidelines, and don't neglect your studies."
His words brought the students back to reality for a moment.
Of course, it was only a brief return to reality. After the lesson, they would probably go back to their old ways. It would likely take until the Triwizard Tournament's champions had been selected and the initial excitement had worn off for them to see things clearly.
As soon as Sherlock finished speaking, Harry leaned over and whispered to Ron and Hermione.
"Before, I might have thought it was impossible for a fourth-year student to be chosen, but after Professor Cavendish said that, nothing seems impossible any more."
Hermione immediately dismissed the idea.
"Probability! Don't talk about Professor Cavendish's jinx without considering probability. What do you think are the chances that a judge would choose an ineligible student under normal circumstances? Not even one per cent. Professor Cavendish's jinx isn't that powerful, so it's simply not going to happen."
Ron was still unwilling to give up.
"But what if? What if a fourth-year student really is chosen?"
Hermione rolled her eyes.
"There is no 'what if'! Just give up on the idea and concentrate on the lesson. You're already in your fourth year. Just imagine how Mrs Weasley will react if you don't bring home a single OWL in your fifth year!"
Of the three, Hermione was always the one who managed to remain rational. After bringing Harry and Ron back down to earth, she turned her attention to the lesson.
"Your fourth year marks a turning point in your seven years of magical education. From this year onwards, both Charms and Transfiguration will begin to delve into advanced magical knowledge."
"If the magic you learnt in your first three years could be mastered simply by applying yourself, then from fourth year onwards, some of the material will no longer be so easy to understand."
"So, before we begin, I want to remind you of something. I don't want any student to fall behind this term because of the competition. I don't expect everyone to master those obscure and difficult magical concepts, but the material you should normally be able to learn must not become an obstacle in your examinations."
As he spoke, Sherlock wore a very serious expression. Only after confirming that every student was listening attentively did his expression relax slightly.
"From fourth year onwards, Defence Against the Dark Arts lessons will officially begin to cover genuine Dark Arts. Normally, this subject matter would only be introduced in fourth year, but questions on it have already appeared in the fifth-year Ordinary Wizarding Level examinations."
"So, last year, I suggested to Dumbledore that we advance the Defence Against the Dark Arts syllabus slightly. This year, we'll officially begin studying some of the most notorious forms of Dark Arts in the wizarding world."
The students instinctively held their breath.
Many young wizards understood what genuine Dark Arts meant. They were entirely different from supposedly Dark creatures such as Red Caps.
Some students from wizarding families turned noticeably pale upon hearing what Sherlock intended to teach them.
Their reactions were entirely within his expectations.
Allowing students to encounter knowledge related to the Dark Arts at an earlier age was a decision he and Dumbledore had carefully discussed.
From this year onwards, the wizarding world would become increasingly dangerous, and Hogwarts, which parents regarded as the safest place in the magical world, stood right at the centre of this gathering storm.
Introducing students to this magical knowledge earlier would at least help them recognise danger, ensuring they wouldn't be completely ignorant when it eventually arrived.
Sherlock looked at the students seated before him and asked calmly,
"Can anyone tell me which are the most famous and most evil forms of Dark Arts in the wizarding world?"
The classroom remained silent for several seconds before a few trembling hands slowly rose.
Sherlock called on Ron.
"The Three Unforgivable Curses, Professor."
His voice was very quiet, as though he were afraid of something.
Sherlock nodded gently.
"Very good, Ron. But there's no need to be afraid. Nobody is pointing a wand at you right now. You can speak freely about everything you know. For example, can you tell me which three curses are known as the Unforgivable Curses?"
Ron seemed to gather his courage, and his voice grew a little louder.
"I once heard my dad mention one of them. It's called the Imperius Curse."
"Very good. Knowing even one of them is already quite impressive. Now, can anyone tell me the names of the other two?"
Only Hermione raised her hand, but Sherlock keenly noticed Neville, sitting in the corner, hesitating as though he wanted to raise his hand before ultimately deciding against it.
In the end, Hermione stood and answered the question.
"They're the Cruciatus Curse and the Killing Curse, Professor."