In old age, the human body resembles a grand house or palace whose complex systems are slowly breaking down. As the years advance, a natural trembling takes hold of the physical frame [מצודת ציון, תעלומות חכמה]. The physical elements meant to protect this bodily house begin to fail. The primary approach among commentators is that these protectors are the hands and arms, which start to shake and lose their former coordination. Others suggest these defenders are the ribs and waist that shield the internal cavity [רש״י, תורה תמימה], or the internal forces of digestion and purification that maintain the body's health [אבן עזרא]. Over time, these protective structures warp, shrink, and bend under the weight of weakness [מצודת דוד, רש״י, צאינה וראינה].
The body's foundation of strength also falters [מצודת ציון]. Most commentators agree this points to the legs and thighs. Once capable of supporting the entire weight of the person, they eventually lose their power to stand firm and buckle under the strain. Alternatively, this strength might refer to the arms, or to the hidden internal powers of nourishment and reproduction [תורה תמימה, אבן עזרא].
The decline continues as the body's ability to process food diminishes. Most commentators explain this as the loss of teeth, which become too few to effectively chew meals. Some expand this concept to the entire digestive system and stomach, noting how these organs weaken and struggle to process nourishment [תורה תמימה, צאינה וראינה].
As the physical structure weakens, the light fading through the windows represents the dimming of the senses [מצודת ציון]. The primary approach among commentators is that these are the eyes peering through the sockets of the skull, their vision growing cloudy and blurred. A unique perspective links this imagery to the lungs, suggesting that the darkness is actually the muffling and clouding of the human voice as it loses its clarity [תורה תמימה].
Beyond the physical realities of aging, a profound national allegory connects this decline to the Temple and the study of Torah [תורה תמימה]. In this view, the bodily protectors and forces of strength represent the shifts of Priests and Levites who once guarded the Temple just as guards protect a king's palace. The diminishing ability to process food symbolizes a decline in the deep study of the Mishnah and Talmud. Ultimately, the dimming light reflects the tragic loss of memory and the forgetting of Torah knowledge during the exile, as Torah and memory are likened to light, while forgetfulness is a descent into darkness.