Krishna clarifies that just like fire is enveloped in smoke; a mirror by mal (dirt); an embryo by the womb; Wisdom is covered by desire that is an insatiable fire, which is the constant enemy of the wise (3.38-3.39).
Earlier, Krishna had said that gunas have the capacity to hypnotise (sammohit) us. Desire, born out of rajo guna does the same. He further elaborated (3.40) that the senses, mind and intellect are said to be the seat of desires and through these, desires hypnotise our soul by eclipsing its wisdom.
A mirror is the perfect example of a sakshi (witness). Its wisdom is to reflect both situations and people brought before it without any labelling. It doesn't have the burden of the past nor any expectations from the future and is always in the present. Its effectiveness reduces when this wisdom is covered by dust.
While the metaphorical mirror is our true nature, the dirt is our past accumulations gathered because of our previous motivated actions and desires. Similarly, the ability to know is our true nature, which is limitless, but we identify with the limited knowledge gathered. In a nutshell, the dirt is our past accumulations which include knowledge, pleasant or unpleasant memories and judgements that weigh heavily upon us. Likewise, the desires delude our soul by eclipsing its wisdom.
A careful look at the crucial conversations in the workplace and family would reveal that we carry the heavy burden of our past and find it difficult to appreciate the present moment resulting in lowered productivity and misunderstandings.
Living in the past is misery and the key is to not let the past make us its slave. To begin with, we could use some of it as an instrument to help us till we permanently align ourselves with the present moment of consciousness.
Source - Daily World