All glitters are not gold expansion of idea?

Question: All glitters are not gold expansion of idea?

This line means, that one should not rely on outward appearances, one should only believe in what is inside him. People show off a lot, people show a lot of brightness. To make other people attracted to them, but not every attraction is gold, and "all glitters is not gold" simply means that people shouldn't trust other people's looks. People showing external brilliance are very deceitful people. That's why one should trust only oneself and not on others.