Franz was able to understand the grammar lesson easily because he was:

M. Hamel went on to talk of the French language, saying that it was the most beautiful language in the world— the clearest, the most logical; that we must guard it among us and never forget it, because when a people are enslaved, as long as they hold fast to their language as it is as if they had the key to their prison. Then he opened a grammar book and read us our lesson. I was amazed to see how well    
I understood it. All he said seemed so easy, so easy.