But the dangerous and widespread effects of the permissive principle applied to important rules will be appreciated to the full when we study the interpretation which railroad men in general are in the habit of applying to the word _caution_. On all railroads there are certain fixed signals for the guidance and information of employees. When caution is called for, the light is usually green and the semaphore horizontal. Now, as the writer looks at it, when any signal indicates _caution_, it is not to be looked upon as a permissive or conditional signal to be interpreted at will by different enginemen. According to the rules and to common sense when a train, at the time a cautionary signal is sighted, is running thirty or forty miles an hour, it calls for a positive and not a theoretical reduction in speed. The cautionary signal is not merely a piece of information to be stowed away in the brain of the enginemen, to be utilized when a rear end or a broken rail is sighted. Although for a number of years the inflexible enforcement of the rules relating to these cautionary signals has been advocated, yet to-day train after train will run past these semaphores and green lights without any reduction in speed, provided the track ahead of them is seen to be clear. Here we tackle the very heart of the matter, for in so far as the rules and common sense are concerned, it should not make a particle of difference to the engineman whether the track ahead is or is not known to be clear of trains; his instructions call for cautious running, and by no possible interpretation or juggling with words can cautious running, or running under control, be taken to mean running at full speed. Yet in the way I have indicated the cancer of a very dangerous habit has been allowed to grow into the American system of managing trains. This wrong interpretation of the word _caution_ by enginemen and others has without a shadow of doubt during the past few years cost the corporations thousands upon thousands of dollars and multitudes of human lives. For if railroad managers labor under the delusion that enginemen can run _cautiously at full speed_ when the track is clear, and avoid disaster when from unforeseen reasons another train happens to be on the same section, they are very much mistaken. Practically speaking, then, the permissive principle covers the whole field of railroad life, and is a constant menace alike to the interests of the corporations and to those of the traveling public. As a matter of fact, we, the employees, are bigger than the rules. According to our way of thinking, it is not alone necessary that a rule should be plain and sound from a general standpoint, but its downright meaning and necessity must also be evident in each and every particular instance. If it fails to stand this test, we consider ourselves at liberty to use our judgment in regard to it.