There was a large railroad switchyard in St. Louis, Missouri. One switch, which commenced with a slender piece of steel, headed a train from one main track onto another.
The first track, if followed, would have taken the train to New York City. The other track took the train to San Francisco.
The thoughts we choose are like that. The choice we make concerning potential thoughts may seem insignificant (like a slender piece of steel seems insignificant). However, one “train of thought” could lead us to purity; another could lead us down the track of impurity.
Carefully guard your thoughts because they are the source of true life (Prov. 4:23.) CEV
Source: THE 7 SINS OF HIGHLY DEFECTIVE PEOPLE by Rick Ezell