"Few of the accidents which take place in buildings result from work operations. Most of them occur as a result of other activities in the building and are mainly due to disregard for known safety rules. (Human error is still the weakest link in the chain of accident prevention.) People are inclined to underestimate the importance of safety when moving from one part of a building to another. This everyday function is regarded as such an ordinary, natural, harmless thing that we seem to mentally "turn our backs" on safety precautions."
Good Reading Rack Service, 1956