Discriminative knowledge – viveka is covered the insatiable Kama.

āvṛtaṃ jñānam etena jñānino nityavairiṇā
kāmarupeṇa kaunteya duṣpūreṇānalena ca

kaunteya – O’ Arjuna
jnaninah – of the wise
nityavairina – by the constant enemy
kamarupena – whose form is desire
ca – and
duspurena – insatiable
etena analena – by this fire
jnanam – knowledge
avrtam – is covered

Knowledge is covered by this insatiable fire of desire, the constant enemy of the wise, Kaunteya.

The verse says that just as fire (anala) cannot be satisfied, so is the desire. If you put more fuel, the fire will grow bigger. Likewise, if you fuel the desire with unwanted thoughts, it will give rise to further desires. So desire here is referred to as anala.

Desires themselves are born out of apurnatva, one’s sense of being limited. Each desire is an expression of limitation. One who is discriminating knows only later that the binding desire is useless. For e.g. a person wants to make a huge amount of money on the stock market may say ‘I have a new scheme and I am going to make it work. In 1 months’ time, you will see how great my plan is’. But after the time has passed, all there to see is the person being broke. The person then thinks that maybe I should have thought twice before doing such thing. So there is a discovery phase later. Sankara says that Kama is nityavairi i.e. it is a constant enemy.