Knowledge is enveloped by this (desire), which poses as the relentless enemy of the Knower. In the nature of passion, greed, O Kaunteya (Arjuna), it is insatiable like fire.
Krishna emphasizes how desire eclipses knowledge and instigates one to take to anything wrong, harmful and even devastating. This is so in spite of any inner resistance one feels to its temptation and persuasion.
Krishna describes passion as extremely powerful. Of all the destructive forces at work in the world, that of greed and possessiveness is the worst, most formidable.
For this reason, the Knowers of Truth consider it the foremost enemy, against which any extent of caution and defence will not be excess.
The best way, Krishna says, to illustrate the havoc it works is to liken it to fire, which goes on blazing more the more it is fed. Kāma, in its hunger and thirst, is like insatiable fire.