Sometimes bitterness and jealousy are reasonable. By this he meant that sometimes we have a valid reason, and  it’s logical to have negative feelings towards someone. 

But all because it’s reasonable or logical, doesn’t make it okay. It doesn’t confirm that you’re on the right path, only God does that. This was major for someone like me, because I learned that logic and “what works” for others is not always the right path for us.

Logic and reason only get you so far, there’s something that goes beyond them… something spiritual.