Bhagavān Kṛṣṇa has just identified the inner enemy as kāma and krodha, born of rajo-guṇa. Now he explains how that enemy works. Kāma does not always destroy knowledge completely in one stroke. More often, it covers the buddhi, the discriminative power, so that the person cannot think clearly at the needed moment.

The first image is fire covered by smoke. Fire has light. It should illumine. But when smoke covers it, the light becomes unclear. The fire is still there, but its illuminating power is reduced. This represents a mild form of desire. The person still has discrimination, and with a little viveka, the desire can be cleared.

The second image is a mirror covered by dust. A mirror should show the face clearly, but when dust covers it, it cannot reflect properly. This covering is stronger than smoke. It needs wiping, sometimes repeated effort. This represents a more settled desire. The person may need discipline, repeated reflection, prayer, and sometimes the experience of suffering before clarity returns.

The third image is a fetus covered by the womb. The child is alive, but it cannot function freely. It must remain there until maturity comes. This represents a very deep and intense desire. Such desire cannot be removed by one lecture or one moment of advice. It may need long growth, life experience, karma-yoga, maturity, and time.

So the verse teaches two things. First, desire covers knowledge. When kāma is active, the buddhi cannot do its job properly. Second, not all desires are equally strong. Some are like smoke and can be removed quickly. Some are like dust and need effort. Some are like the womb and require patience and maturity.

This is why spiritual life requires self-observation. We must learn: what kind of desire is this? Can I remove it by viveka? Does it need discipline and repeated effort? Or is it so deep that I must patiently grow through karma-yoga until I outgrow it? The goal is not self-condemnation; the goal is honest diagnosis and proper handling.