“Of course it is happening inside your head, Harry, but why on earth should that mean it is not real?”

Simplified Meaning:

Sometimes, things that happen in our imagination or thoughts can be just as important or real as what happens in the physical world. Just because something is in your mind doesn't mean it isn't meaningful or doesn't have an impact. For example, if you're dreaming about solving a difficult problem at work or school, and you come up with a good idea in the dream, that idea can help you in real life. Similarly, when you imagine talking to a friend about something that's bothering you, even though the conversation isn't real, it can help you sort out your feelings and find a solution. Memories and dreams shape who we are and how we behave. A kind memory can make you feel happy and remind you to be kind to others. This quote encourages us to respect our thoughts and feelings, understanding that they play a crucial role in our lives and in how we interact with the world around us.