Answer: historian

AnswerCrossword Clue
HISTORIANArnold Toynbee, for instance.
HISTORIANCommager is one.
HISTORIAND. S. Freeman, for instance.
HISTORIANCalling of Arthur Schlesinger Jr.
HISTORIANGibbon, for one.
HISTORIANCommager or Beard
HISTORIANPaleologist
HISTORIANExpert on eras
HISTORIANGood person to ask "What happened?"
historianAn expert in or student of history, esp. that of a particular period, geographical region, or social phenomenon
historiana student of history