retrospection       
noun [ U ] uk/ˌret.rəˈspek.ʃən/ us/ˌret.rəˈspek.ʃən/
 回忆
the act of thinking now about something in the past
  a time/mood of retrospection 用于回忆的时候/心情 
 Retrospection just isn't in his nature. 他的天性就是一往直前,绝不留恋过去。 
 See: retrospect
 - More examples
 - He is a man of action, not retrospection.
 - In rare moments of retrospection , my mother would tell us about her childhood.
 - Her message was filled with retrospection but largely devoid of emotion.