When the core of a nation is diseased, can anything else be healthy?
Isaiah uses a powerful metaphor: 'The whole head is sick, and the whole heart faint.' This isn't just about individual sins; it's a systemic illness affecting the very centers of thought and emotion, the 'head' (representing intellect, decision-making, leadership) and the 'heart' (representing will, desire, emotion, the core of a person).
The commentators emphasize that this means the leadership and the core values of the nation are corrupted. It's like an epidemic where the brain and the vital organs are failing. There's no soundness left. This pervasive sickness explains why the external punishments are so ineffective. The problem isn't on the surface; it's deep within the nation's spiritual and moral constitution. When the 'head' can't think rightly and the 'heart' can't feel rightly, the entire body politic is in a desperate state.