a familiar and wise saying, e.g. 'Beauty is only skin deep'

saying or proverb

a short statement expressing a general truth (usually from a known literary work)

saying expressing a belief, often true

a true statement that is obvious, such as 'All humans are mortal'

principle

a short sentence or phrase used as a guide or rule of behaviour, as used by a school, club etc or expressed as a personal rule of conduct

saying, slogan

an order, law or custom which guides or controls behaviour or action; a habit; authority; to govern (people, a country etc)

standard, principle of behavior