An ur-proverb would be a proverb that underlies many others. It would be the most abstract formulation of an idea found in many other proverbs.
Pathei mathos: Learning comes from suffering. (La letra, con la sangre entra.)
The ideology of proverbs is cynical conservatism. Powerful people will exercise their power. You will be judged by the company you keep. Older people know more than younger people do. You will suffer if you don't follow the customs of people where you are. Friends are likely to betray you. Any part of this folk wisdom will be an ur-proverb.