Maturity does not necessarily mean understanding. Maturity means acceptance. Not think, but KNOW the nature of existence. Not hope but appreciate that nothing, NOTHING that happens to you is ever personal. Maturity means identifying with how insignificant yet relevant your actions could and should be. It means identifying your own ground to stand without support. It means to judge yourself, not in eyes of others, but in your own.
But its not a thing that will necessarily lead you to peace of mind.