Olly was confused. He sort of understand what this Fianto Duri spell was supposed to accomplish, but not completely. Keep one spell going so you could do another spell. But that would require performing another spell that allowed you to do another spell? That didn't make sense to him. He was staring up at Professor Hirsch in confusion as he tried to riddle it out. He raised his hand and hoped the man would be able to explain it better to him.

"But if you're doing a spell that requires constant focus, which would mean you can't do another spell, how would you do this spell? It's still just another spell, is it not?" His question could have been worded better but he hoped he conveyed his confusion.