Explain the meaning of line sensation of dying... Fear It can produce. I've understood what it means but I mean what does it mean here in the story not like the meaning of a line in english.

Douglas says that he had experienced both the sesation of dying ie.how one feels when he is about to die and the fear that is produced by death itself ie. one is terrified just by thinking about death.So, he has experienced both the aspects of fear that death produces.