Professor Morgan does the two-claps again; shields fizzle out across the classroom.  "Nice work, everyone," he says.  "Point to Clover of Slytherin for being the first to get it; point to Hermione of Gryffindor for giving good casting advice to two other students."

(She turns a brief and perfunctory childsface towards Hermione of Gryffindor.)

"Next we'll see how it feels to really use a shield spell."  He turns away from the students, toward an open closet door at the back of the classroom, and whistles with his fingers.

A procession of multicolored beanbags, looking very like the muggle sort except for floating through the air under their own power, emerges from the closet.  They huddle up in an amorphous cloud next to him.

"Each of you will pair up with a beanbag.  It'll wait for you to cast a shield, then throw itself at it.  If the shield's good, it'll bounce off.  If it's okay, it'll break the shield but be slowed down.  If it's no good, it'll go right through it and hit you."

"They don't hurt to get hit by - go on, show 'em," he adds to the cloud of beanbags, and one shoots out to slap him in the face and fall to the ground.  There's a titter from the class.  "They'll hit harder if you tell them to, but never hard enough to do more than sting a little.  Everyone come on up and pick your favorite color."

She nabs a red one.

She casts the shield again, feeling that antsy state of not being able to tell what it is she's keeping still but trying very hard to keep it still anyway, and it's steady.

The beanbag thwaps itself at it.  There's a sparking, zapping sound, and the glimmery lights around the border of the shield flare in brightness, and there's some other sensation, a jolt at the part of her body or mind or whatever that corresponds to keeping the shield up; but it holds, and the bag bounces off it.

She lets go of the shield, rests her focus for a moment, casts another.

Bag hits, and this time she knows it's coming and braces for it, and the lights stay much steadier and the zapping noise isn't there at all, and the bag bounces off again.  Somehow the second time it looks a lot less like it's bouncing off a magical screen of energy and more like it's bouncing off a plain ordinary wall, which she's going to guess is a good sign.

"Harder," she says to the beanbag, and this time the noise is louder, the lights around the edge sparking and jittering with the impact.  "Harder" again, and the bag moves less like it's been gently tossed and more like it's been thrown, and there's a pop of electricity as the shield vanishes, the little glimmering lights skittering away into the air like dots in a bright blue sky, and the bag tumbles sadly through the air and lands on the ground, maybe six inches past where her shield had been.

"Don't take it up so fast," Morgan says to her.  "Stick with one level until you can keep the shield nice and steady when it hits."

Mrgh.  Okay childsface on bright studious nod.  She swirls her wand again to bring up a new shield.

To the beanbag: "Down a notch, go for it."

Thwap.  Shield breaks again.

Well that's not fair.

"Try casting it again.  Two strokes, remember, don't try to make it all one loop."

Bright studious nod.  ...and she supposes she'd better actually take his advice.

Stroke swoop stroke "oppilo;" shield forms.

Thwap.

The shield holds!  She produced a self-satisfied smile, for Morgan's benefit, though she is actually feeling pretty self-satisfied.

"There you go," Morgan says.  "You've gotta be really precious about getting the gestures right, especially when you're just learning a new spell.  Go a few more rounds with it."  He indicates the beanbag, which has resumed floating attentively.

She nods, and turns her attention back to the beanbag.  And doesn't tell it to speed up quite so often, and is more careful with her gestures, and also tries to keep her face on more consistently as she's working.

After a little while of this he does the two claps again at the head of the classroom.  (All the beanbags desist their thwapping and sort of hover at attention.)

"All right," he says, "looks to me like everybody's got a pretty decent handle on it.  Good work, folks.  Now I'm gonna open the floor to questions - about oppilo, about defensive magic in general, about magic in general.  It's normal to have questions or doubts the first time you ever do intentional magic, so, shoot."

"I can sort of keep the shield going if I concentrate but I can't really - tell what I'm doing, to keep it going, if that makes sense - am I doing something wrong?"

"I've seen real duels between grownup wizards and they don't have to be careful with the gestures, why can't we just cast the spells that way?"

"What good is a shield that just stops beanbags, if dark wizards are going to be throwing hexes at us?"

"You're not doing anything wrong.  Part of learning to do magic is learning to feel your own magic, and understand what its doing inside you, and how to make it do other things.  It's like if you're trying to train a muscle you've never used before, except that making it stronger than it is now is the only way you'll be able to even tell it's there or what it's doing.  I can tell I'm doing something, but not what I'm doing or how I'm doing it is exactly what you're supposed to feel like the first time you cast a spell."

"When you're very very good at a particular spell, and very very good at casting spells in general, you can afford to be sloppy with your gestures, or even leave them out altogether - that's called stillcasting, and it's an important skill for defending yourself.  But the way you get good enough to stillcast a spell is by practicing casting it gesturewise, a lot and very carefully."

"Different enemies will attack different ways.  Some dark creatures attack in ways better blocked by ballistic shields; some attack spells create magical constructs that are more like physical objects then spellbolts.  And lots of good anti-hex shields are broken easily by physical objects, or just let them right through, so if you only use anti-hex shields your opponent will attack with projectiles instead.  And once you're stronger and better at casting oppilo then you are on your first day of lessons, it can block a lot more than a beanbag."

Hermione of Gryffindor raises her hand.

"Shoot."

"What makes dark magic dark?"

(Clover's outward persona wasn't going to ask this particular question on her very first day of classes in front of everybody, but now that someone else has she's very interested in Professor Morgan's answer.)

"Whoof," he says.  "That's a big question."  He sits down on his desk.

"Well, first of all - the class is called Defense Against the Dark Arts, but it's perfectly possible to use spells that aren't dark to hurt people, and you'll be learning to defend yourself agains those as well.  But dark magic..."

He muses.  "Well, to explain it properly I should say that different magics can be more or less similar to each other in lots of different ways, it's not just a matter of dark versus not dark.  A cutting hex and a puncturing hex are more similar to each other than either is to a bashing hex.  All three of them are more similar to each other than they are to the shield spell we learned today.  And cutting hexes and shield charms are more similar to each other than they are to a flame-freezing charm, and so on.  It works across different domains of magic, too - self-transfiguration with a wand and animagy and brewing polyjuice potion are in a meaningful sense more similar to each other than wanded self-transfiguration is to, say, a summoning or fetching charm."

"What it means for magics to be similar is complicated, but basically, if you get good at one spell, it makes it easier for you to get good at other spells and even potions and rituals that are similar to it.  You can't learn to be an animagus just by practicing brewing polyjuice, but someone who's brewed polyjuice before, and done a lot of other transfiguration besides, will have an easier time learning to do the things you need to do to become an animagus."

"Dark magic is essentially a broad set of spells and potions and rituals and other magics that are all similar to each other in this way, and tend to have other things in common.  They are very often primarily or solely useful for violence; they are very often harmful to the user, or require the user to cultivate self-destructive or dangerous mental states; they frequently distort their users' or targets' bodies in unpleasant or unsettling ways.  But even dark spells that don't do any of these can be dangerous to use, because they make you into more the sort of person who's good at dark magic, and that's not always a good kind of person to be, for you or for the people around you."

"There's more I could say on the subject than that, but I think that's a pretty good primer for your first day."

...Yeah this all sounds to her like dark magic is perfectly reasonable to use, and Professor Morgan is just repeating cliches.  What on earth is a "dangerous mental state", presumably if you are adopting a dangerous mental state it is because you endorse being dangerous at that moment.  Plenty of combat spells could be described as "primarily or solely useful for violence," and ordinary damage-to-a-body inflicted in the course of fending off an attacker is also "distorting the target's body in an unpleasant or unsettling way."  And it is her body and she may distort it how ever she likes in fact.  And being the sort of person who is good at dark magic seems strictly better than the alternative, because a person who is good at dark magic can simply elect not to use it if the situation does not call for it.  (This seems analogous to how an evil person may choose to be good when it advantages them, but a good person may not choose to be evil without ceasing to be good, evil people thus being strictly advantaged over good ones - this principle having always seemed self-evident to her.)

If she was feeling impressed with her defense professor at the beginning of the lesson, that does for that.  Oh well.

There are a few more questions asked that Clover does not find terribly interesting, and then the class ends.