Tobermory Explained:

Theme: I think the theme is that we aren't necessarily  open to new ideas. When Appin introduced the cat, he was speaking the truths of everybody at the social gathering. The people there belong to a higher class of society and tend to be stuck up and snotty. Therefore when the feline was telling the truths of everybody there, they took it to offense and thought the cat was rude, and they were mad at Appin for introducing the cat. I think theme goes for all of us because most of us aren't open to new ideas. Whenever I go to a restaurant my parents always try to get me to try new foods and I'm never open to it, because I like being comfortable. The same goes for society, as they like to be comfortable and content with the way things are instead of change. 

Tone: I think the tone is a wrathful and hateful one. The people were upset with the cat for what it said, and they were also upset with Appin. That's why they said that if he was trying to teach him German verbs he deserved all he got. The people there had a feeling of hatred for the cat and Appin for embarrassing them.