ישעיהו, פרק מ״ד, פסוק י״ח

The profound foolishness of idol worship stems from a complete internal blockage. It is an absurdity to bow down in worship to a block of wood, especially when the other half of that exact same log was just used as fuel to heat an oven and bake bread [צאינה וראינה]. Yet, people fail to make this simple, logical connection because their minds and senses are essentially plastered shut, covered over as if a wall were smeared with thick clay [מצודת ציון, אבן עזרא, ביאור שטיינזלץ].

Idolaters suffer from two distinct types of perceptual failure. First, they lack basic knowledge, which is normally gained through the physical senses and life experience. Their physical eyes are covered and cannot perceive basic reality [מלבי״ם]. Second, they lack deeper intellectual understanding. Their internal faculties for reason and logical deduction are entirely sealed off [מלבי״ם]. Some even map this process physically, placing sensory knowledge in the front of the brain and deeper logical understanding in the middle [אבן עזרא]. When both the physical senses and the inner intellect are completely impaired, it is no surprise that a person cannot see the emptiness of their own beliefs [מלבי״ם].

There are different perspectives on what causes this severe blindness. One approach views it as the result of an outside force acting upon the person [אבן עזרא, רד״ק]. Within this view, some suggest that God Himself seals their minds as a punishment for their actions [אבן עזרא, רד״ק]. Others argue that a person's own evil inclination is the culprit, overpowering their intellect and covering their eyes to hide the truth [מצודת דוד, רד״ק]. A different perspective suggests there is no external force at work at all; instead, this blindness is simply a natural, existing state in which their vision and understanding are already completely shut [שד״ל].