It seems unfair that the slightest unplanned and unwanted sighting of impurity should deal more merciless blows to someone who guards himself than to someone who doesn’t. While others around seem to be unaffected as if anaesthetised and having no issue with it at all, the shmiras einayim stalwart can be knocked right off-balance with even one glimpse. Alone, he faces the question, “Am I, perhaps, making my own problems by guarding my eyes so carefully? Is this the way things are supposed to be?”
A famous story of the Chafetz Chaim helps us answer this question. Once, the Chofetz Chaim was witness to Yidden driving cars on Shabbos. He cried bitterly at this brazen chillul Shabbos. When he saw the same chillul Shabbos a week later, he cried yet again. However, upon realizing that his crying the second week was less passionate than the first, he began to cry intensely, for his own lack of sensitivity which he felt had been dulled so rapidly.
Surprisingly, we see the answer. Acute sensitivity is a very good sign indeed. The violent response speaks of his refinement and high quality. Kedusha heightens our sensitivity to finer feelings. The skilled violinist will have tightened his strings until they resonate to the lightest touch of his bow.
On the contrary, it is the tumah of unrestricted viewing that brings on staleness, increases sluggishness and deadens our innate sensitivities. Only a healthy, well-cared-for neshama could react so acutely to a minor stimulus. The whiter the shirt, the more pronounced each speck of dirt. The Vilna Gaon, ztz״l, related that even hearing the footsteps of a woman was enough to disturb his kedusha. Similarly, Reb Chatzkel Levinstein, ztz״l, said of himself that traveling through the streets of Tel Aviv – even without looking out of the car window – would have a harmful effect.