In the Potions Classroom, Will was discussing Potions with Snape.
"Behrens, stay away from the crackpot stuff in the Restricted Section, like Potion Transfiguration. Take a good look at these books instead. Quite a few cover the principles behind Potions. That's what you should be studying." Snape handed Will a slip of paper.
It listed several books, including Potions Unveiled, The Foundations of Potions: Pharmacology, and Strange Potions.
"Of course, I don't expect that Troll-sized brain of yours to make sense of such complicated books anytime soon. In fact, your chances of understanding them before next year are about the same as Merlin's chances of climbing out of his coffin."
Will had grown immune to Snape's venom. He simply filtered out every insult the man threw at him.
While Snape was still demonstrating his talent for attack, a small white bird flew into the Potions Classroom. It landed beside his hand and turned into a slip of paper.
Will studied the note curiously. The bird it had become had moved so vividly that he never would have guessed it was the work of Transfiguration.
Snape glanced at the note, and his expression darkened visibly. "We'll discuss any questions later," he said.
Then he hurried off, his billowing black robes looking remarkably like a bat's wings.
Will didn't mind being abandoned. He headed straight for the storage cabinet in the corner, hoping to find a particular notebook.
The cabinet held plenty of Potions ingredients and several battered Potions textbooks. Will leafed through them one by one until he found what he wanted.
At the bottom of the back cover, a tiny line of handwriting read: This book belongs to the Half-Blood Prince.
Advanced Potion-Making, filled with notes in Snape's own hand, wasn't particularly difficult for Will. Books on Potion Brewing listed