And how much better to die in all the happy period of undisillusioned youth, to go out in a blaze of light, than to have your body worn out and old and illusions shattered.
Source, in full
Letter to his family (18 October 1918); published in Ernest Hemingway: Selected Letters 1917–1961 (1981) edited by Carlos Baker. It was also published in The Oak Parker (Oak Park, IL) on 16 November 1918. Only 19 years old at the time, Hemingway was recovering from wounds suffered at the front line while serving as a Red Cross volunteer.