Luther thought 'Seems like father's notes work.' with a small shy smile on his face.

After the professor's question, he thought for a while and tried to remember what was written in his father's notes. Then with a slightly unsure tone, he said "I think, the potion's effect cannot overcome powerful enchantments or it is less effective against them." To the end of his sentence, his voice rose involuntarily ever so slightly belying his uncertainty.