Bhagavad-Gita: Chapter 3, Verse 39

Rudra Vaisnava Sampradaya:

Visnuswami

Sridhara Swami's Commentary

Now the inimical nature of kama or lust is being made even more explicit by Lord Krishna.

It is the discriminative faculty of knowledge that is covered by kama. To the ignorant while enjoying sense objects kama itself is the cause of pleasure; but the subsequent reaction will be inimical. To the person situated in Vedic wisdom who understands that they will receive a subsequent reaction, then kama is a cause of pain even while trying to enjoy. Therefore kama is understood to be an eternal enemy. Moreover even if supplied with delightful sense objects of enjoyment it is never enough because kama is insatiable and when it is not satisfied kama turns to krodha or anger and that leads to grief and affliction just like a forest fire burning everything in its path. So from these statements its eternal inimical nature towards all beings has been declared.

Brahma Vaisnava Sampradaya:

Madhvacarya

Madhvacarya's Commentary

One on the path of jnana yoga knows from the Vedic scriptures that moksa or liberation from the cycle of birth and death can never manifest itself until first attaining atma-tattva or soul realisation. When such is the case for persons of wisdom what can be said for persons of meagre intelligence. The word kama-rupena means in the form of lust. This indicates that only with great pain and difficulty is lust ever fulfilled. The word duspurena means never satisfied. This indicates that kama or lust is an eternal adversary. Even the position of Indra in the heavenly realms is born of this kama that is to be the king of all the celestials; yet even while trying to achieve the position of Indra, the position of Brahma is sought because kama is never satisfied and it is more exalted to be the ruler of the material worlds then the king of the celestials and so forth and so on. The word analena means like a fire which denotes the burning fire of kama which is never satisfied and insatiable. It is said that kama covers the atma as smoke covers fire, As dust prevents one from seeing a reflection in the mirror this kama prevents one from perceiving their atma and as the womb imprisons the embryo it is kama which keeps a person imprisoned in the material existence. This is Lord Krishnas meaning.

Sri Vaisnava Sampradaya:

Ramanuja

Ramanuja's Commentary

The intellect of one who even has understanding of atma tattva or soul realisation becomes clouded by the eternal enemy known as kama or lust and which generates fascination and excitement for enjoying the objects of the senses. The word duspurena means insatiable, it can never be satisfied. It constantly hungers for sense gratification even if it is inaccessible to get and impossible to have still kama yearns for it. It is anala or inexhaustible as nothing ever completely satisfies kama permanently. When the object of its desires has been acquired and the senses fully gratified then at once kama wants more and looks for something new. It is never satisfied. In what way kama utilises itself to envelope the atma or soul Lord Krishna reveals next.

Kumara Vaisnava Sampradaya:

Nimbaditya

Kesava Kasmiri's Commentary

Here Lord Krishna illustrates the inimical nature of kama or lust with three lucid examples concluding that discriminatory knowledge of even basic right and wrong and even common sense is completely neutralised by the influence of kama causing one to act in base and degraded ways. The ignorant though are always pursuing kama because they derive pleasure while enjoying the sense objects afterwards when they feel the pain of the reaction they are forced to accept they may see kama as an enemy. The person situated in Vedic wisdom sees kama as an enemy from the beginning even while contemplating enjoying the action and later if they actually consumate the action then they know a painful reaction is forthcoming. Thus for those of Vedic wisdom kama is known as being an eternal enemy.