To be famous, it is the state or quality of being widely honored and acclaimed. The dictionary lists fame as:
-Noun: 1. widespread reputation, esp. of a favorable character; renown; public eminence: to seek fame as an opera singer. 2. common estimation or opinion generally held of a person or thing; reputation.
–Verb (used with object): 3. archaic. to have or spread the renown of; to make famous.
For the most part, all the people quoted in these volumes are very famous people!