This question leads to endless answers, but I'll try my best to sum it up.
Good can be with good intentions. The action is not what matters, but the intention of doing good or evil. If you intend to help other people, not yourself, that is a good action. The difference would be your intention.
Good and bad may also be seen as an opinion. Good music, good books. The difference would be your opinion on the matter.
Good is something you should strive to be, and to be 'bad' would be something you would try not to be.
These lines would best fit an old, philosophical doctor based on his language use. A farmer and uneducated trader and a vagrant wouldn't be able to speak in such a manner probably.
