A flag is a symbol of great power and beauty and great history.  Here are two quotations from the founder of the Vexillogical Institute Whiston Smith.

"Flags represent the presence, origin, authority, possession, loyalty, glory, beliefs, aspirations of a person, an organization or a political entity. 

 They are employed to honour or dishonour, warn and encourage, threaten and promise, exalt and condemn, commemorate and deny."  "To display a flag is to participate in a group or a philosophy that spans time and distance; it is to express ones own views to others in a concise but dramatic form...