Many traditional industrial engineering and work-study projects are of the passive breakthrough type, particularly when left to the initiative of the I.E. or work-study department. Of course, IEs also work on enforced breakthrough activities initiated by management or by crisis, but passive breakthrough activities, led by IEs, have probably been the greatest source of productivity improvement this century. Many of Taiichi Ohno's activities could be classified as passive breakthrough. Apparently he was a great experimenter in the dead of night.