THOUGH it would seem that the sane and simple message of this essay could not be misconstrued, the fact that it has been wholly misunderstood in newspaper comment warns us that it is necessary to preface it by stating that it does not counsel all persons to drive themselves at all times beyond the limits of ordinary endurance, that it is not a gospel of over-strain nor an advocate of the use of alcohol and opium as stimulants in emergencies. It states that "second wind" is a reality in the mental as in the physical realm and that it can be found and used when needed - nothing more.

Essays in Radical Empiricism By William James