What is the meaning of the phrase all for one and one for all?

Answer 1

Unus pro omnibus, omnes pro uno is a Latin phrase that means "One for all, all for one" in English. It is known as being the motto of Alexandre Dumas' Three Musketeers and is also the traditional motto of Switzerland.
In 1868 officials launched an add campaign using that phrase ("Unus pro omnibus, omnes pro uno") to evoke a sense of duty due to widespread flooding in the alps and solicitations for donations as well as charity work. It is still the unofficial motto of Switzerland, and may have originated in a book / play of "The Three Musketeers" (1844). Generally the intent of the saying is to stand as a united group against all attacks upon the group, the sacrifice of one for that group being a noble thing to the group.