Possible Clues:

• "Elder" of ancient history
• Noted Vesuvius observer
• Roman writer who originated the phrase 'with a grain of salt'
• Roman writer, Elder or Younger
• The Elder or Younger of Roman history
• "The Elder" of Rome
• The Elder or the Younger of Rome
• ''Elder'' Roman historian
• Roman Elder or Younger
• -- the Younger, c62-c113AD, Roman writer and administrator