All living beings, even those with knowledge, have to act according to their nature; what can anyone gain by repressing their nature? (03.33) That repression is futile doesn’t mean that one should just cave in to one’s default attachments and aversions; they need to be watchfully regulated while focusing on one’s natural duties (03.34). It is better that Arjuna meet with destruction while doing his natural duty as a kshatriya rather than adopt someone else’s natural duty, say, the brahmin’s duty of non-violence — adopting another’s duty can have fearful consequences when Arjuna’s repressed kshatriya nature resurfaces and impels him to act violently when it isn’t necessary for social maintenance, as it is now (03.35). 

Pondering Krishna’s strong warning, Arjuna seeks to know the force that impels one to act self-destructively, as if by force, against one’s will (03.36). Differentiating this force from one’s nature, Krishna identifies it to be lust, which degenerates into anger — it is everyone’s voracious and vicious enemy (03.37). Lust misleads people by covering their knowledge to varying degrees: slightly as smoke covers fire; significantly, as dust covers a mirror; and substantially, as the womb covers an embryo (03.38). Thus covering people’s knowledge, lust acts as their eternal enemy, tormenting them internally with the fire of insatiable desire (03.39). Helping Arjuna understand how lust obscures our knowledge, Krishna specifies its inner hideouts: the senses, the mind and the intelligence (03.40). Recognizing lust to be the portender of sin and the destroyer of knowledge — and even the inclination to seek knowledge — one needs to begin combating it by first regulating one’s senses (03.41). To engage in this inner war more effectively, Krishna outlines a relevant hierarchy: above the outer world filled with tempting objects are the senses; above the senses is the mind; above the mind is the intelligence; above the intelligence is the soul proper (03.42). Using his intelligence, when Arjuna understands his spiritual essence and situates himself in steady self-awareness, he can win his life’s biggest battle, defeating the formidable enemy of lust (03.43).