"You are here to learn the subtle science and exact art of potion-making," he began . He spoke in barely more than a whisper, but they caught every word--like Professor McGonagall, Snape had the gift of keeping a class silent without effort. "As there is little foolish wand-waving here, many of you will hardly believe this is magic. I don't expect you will really understand the beauty of the softly simmering cauldron with its shimmering fumes, the delicate power of liquids that creep through human veins, bewitching the mind, ensnaring the senses.... I can teach you how to bottle fame, brew glory, even stopper death--if you aren't as big a bunch of dunderheads as I usually have to teach."
~The Philosopher's Stone, Ch. 8 "The Potions Master"
I thought I'd give you the very first time we see Snape. It's so easy to imagine his voice here... It gives you chills, doesn't it? I melt into a puddle every time I read or watch this scene. Ensnaring the senses, indeed...
Everyone has had that one horribly mean teacher... But for every hundred students that hate that teacher, there's one girl (or guy, I don't judge) that has a massive crush on him for an unexplainable reason. That girl would have been me. Just by this speech, I'm sure that I would love Potions class. And I'd be like Hermione--ready to prove that I wasn't a dunderhead. But I'm not show-offy person. Plus, I'm sure I'd be a Slytherin, so he'd have another reason not to be a jerk to me.
And you know what's weird? I used to use the insult "dunderhead" all the time. Way before I knew what Harry Potter was. I feel awesome.