Bhagavad Gita Verse 52, Chapter 2

yada te mohakalilam buddhirvyatitarishyati |
tadaa gantaasi nirvedam shrotavyasya shrutasya cha || 52 ||
 
When your intellect has completely crossed over the quagmire of delusion, then you will become indifferent to what has been heard and what is to be heard.
 
yada : when
te : you
moha : delusion
kalilam : quagmire
buddhih : intellect
vyatitarishyati : completely crossed
tadaa : then
gantaasi : attain
nirvedam : indifference
shrotavyasya : what is to be heard
shrutasya : what has been heard
cha : and
 
As we saw in the last shloka, Shri Krishna concluded the introduction to Karmayoga. Now in this shloka and the next, he offers us pointers to assess whether we are progressing on the spiritual path or not. He mentions that one who is always established in equanimity becomes indifferent to hearing about any topic. But that is just the literal meaning. Here it also refers to seeing, touching, feeling and smelling, i.e. any object perceived through our senses.
 
Let's look at this in more detail. Also note that it we have gone through similar situations already in our lives, so this should not be something unknown to us.
 
Growing up as a teenager in the 1990s, WWF wrestling was considered a phenomenon. We would watch it diligently when it came on TV, read about it in magazines, and discuss it among friends non stop. But as we grew up we realized that it was staged entertainment, and not a real sport. And in time, like many other things, we outgrew the fascination for it. So now as adults when we see WWF on TV, we just change the channel and don't even think twice about it. We have become indifferent to WWF.
 
Now a wonderful poetic phrase - quagmire of delusion - is used here. What exactly is moha or delusion? In case of the WWF, we were under the delusion that WWF would give us happiness. But more broadly, moha refers to the error of pursuing of the material world as a source of happiness, as opposed to realizing the eternal essence. Therefore, as one practices equanimity and moves ahead on the spiritual path, the material world slowly loses appeal.
 
So as you begin to practice equanimity through performance of svadharma, try to keep track of your attachment to material objects. You will begin to observe that slowly, your attraction to the material world will start to weaken. This state of ultimate indifference to the material world is the state of "param vairagya" or ultimate indifference.
 
This shloka is the seed of chapter fifteen of the Gita, where this topic of ultimate indifference or dispassion is covered in great detail.