Chapter 2, Verse 62
dhyāyato viṣayān puṁsaḥ
saṅgas teṣūpajāyate
saṅgāt sañjāyate kāmaḥ
kāmāt krodho’bhijāyate
In him whose mind dwells on the objects of sense with absorbing interest, attachment to them is formed. From attachment arises desire. From desire, anger comes forth.
Here Krishna doesn’t say that you must let go of everything: he is talking about how to let go. This is very important. He says that by constantly dwelling on the objects of enjoyment, the human being develops an intense form of attachment to them. This is true. When the senses dwell on things, like lust and drugs and other things, when the mind and the senses dwell on these many things, you become attached to them and you are not free. This creates more desire to gain even more things.
When one dwells on even one enjoyment in the mind, one gets attached to it and finds it very difficult to let it go. And then you create not one, but many more desires. Krishna says, “All these people who are in front of you on the battlefield, Arjuna, these are all the qualities which arise due to desires. And it takes only one desire to create many more attachments.” Duryodhana doesn’t want to let go of his attachment to the kingdom. From his attachment to the seat of Hastinapur have arisen so many desires to gain more and more. That is why the Kauravas also took Indraprastha: they wanted to conquer everything. This is also true in our daily life, when we become obsessed or controlled by greed, pride, and the ego. From one desire, more desires arise. It is never enough. One becomes greedy. This is how attachment gives rise to desires, and when a hindrance appears in the fulfilment of these desires, one becomes angry. “Why didn’t I get this? Why did my neighbour get that? Why not me?” This anger then becomes hatred.
Bhagavad Gita