“Accident-prevention engineers must know why and how accidents occur; they must know the causes of accidents and direct their attack to the removal of those causes, instead of selecting a remedy blindly or arbitrarily.
Natural laws are favorable in this work, in that the first departure from safe conduct does not necessarily result in an injury but must, in the average case, be repeated several hundred times before the inevitable penalty is exacted. In the recognition of this fact, and in the knowledge that these hundreds of unsafe acts and mechanical hazards that precede an injury are all visible, lies the opportunity to attack successfully the problem of accident occurrence.”
Industrial Accident Prevention – A Scientific Approach, H. W. Heinrich, Assistant Superintendent Engineering and Inspection Division, The Travelers Insurance Company, 1941
