Casimir mentally cursed as Artemis put the tome away. He really wanted, felt he needed, to know more about its contents and what it had to teach. It was a mystery why he wasn't placed into Ravenclaw when he first arrived at Hogwarts, because knowledge was one of the main things Casimir frequently sought to set himself apart from others. Perhaps, once they all had arrived at Hogwarts, he could try a variety of methods to get the book from Art... asking politely was one option, but after hearing the implication of the trouble he had gone through to get his hands on such a tome, Cas figured the guy wouldn't be so willing to just give it up.

"Seventh year. You are in, what, your third or fourth year?" Casimir asked Artemis. The boy seemed to be a wary and cautious individual, so speaking in a more relaxed and even casual tone should be the best option when interacting with him.