This quote is encouraging a person to be true to themselves and not be ashamed of the things that make them unique, even if they are considered to be nutty or strange. The inner moonlight refers to someone’s true self, and the madness refers to the unconventional, creative ideas that come out of that part of a person. So this quote is reminding people to follow their instincts and express themselves, even if it feels a little unusual or “madâ€.