What does Imogen do wrong?

She drops a book

Again and again you slash the vicious quirt into your student's silken flesh, building a crescendo of agony breathtaking in its intensity. **** sobs and wails alternate with periods of inaudible speech, as if Imogen is praying or trying to give herself encouragement, writhing helplessly beneath your relentless onslaught.

The quirt is light, but the **** of impact is still sufficient to throw off Imogen's balance and as the skin begins to peel from between her shoulder blades, a particularly effective lash sends a wobble through her torso and into her arms, ending in a spasmodic movement of her left hand which sends one of your tomes tumbling to the tabletop.

"Oh, no! I'm sorry. Please, no."

"That was nine lashes," you say, picking up the book and returning it to the back of Imogen's hand. "We can start over…"

Imogen lets out a wail and starts to sob so wretchedly that both books fall from her hands.

"I'll never do it," she weeps, "it'll just keep starting over and never end."

"As I was saying, we can start over or I can tie you to the whipping post in the cellar and give you double the number of strokes that remain. That would be one hundred and seventy-four."

Shoulders quaking as despair threatens to overwhelm her, Imogen splutters and forces out the last words she would ever want to say: "Please tie me to the whipping post and double my punishment, sir."