Bhagavad Gita Verse 53, Chapter 2

shrutivipratipanna te yada sthaasyati nishchalaa |
samaadhaavachalaa buddhistadaa yogamavaapsyasi || 53 ||
 
When your intellect, confused by what is heard, remains steady and stays grounded in equanimity, then you shall attain yoga.
 
shruti : what is heard
vipratipanna : confused
te : your
yada : when
sthaasyati : will become
nishchalaa : steady
samaadhau : in equanimity
achala : grounded
buddhih : intellect
tadaa : then
yoga : yoga
avaapsyasi : attain
 
The last shloka described an advanced stage of yoga, in other words, a state of equanimity, where we begin to slowly lose interest in material objects. In this shloka, Shri Krishna indicates the final stage of yoga where the intellect never loses its grounding.
 
In the initial stages of our spiritual journey, we will begin to experience moments of equanimity. These moments will be short and fleeting, but that is ok. As we continue to practice equanimity, these moments will grow longer and become more frequent. But there is always some thing - a thought from the past, a critical statement uttered by a friend, an object that we crave - that takes us out of equanimity and back into the world of moha. 
 
So what should we aim for? We should aim for something better. Here's an example. When the internet was new, most of us connected to it using a dial-up modem. Each time we needed to access the internet, we had to establish a connection, and then disconnect it once done. As technology improved, we began to connect through it via cable or DSL connections. These connections are "always on", so there was no need to connect and disconnect everytime. Now no one wants to ever go back to using dial up modems.
 
So therefore, this shloka gives us a picture of the most advanced state of yoga where one is always in a state of equanimity, no matter what the circumstance. And when this happens, we will be always connected to the imperceptible, incomprehensible eternal essence. This is the only way to attain the eternal essence. When that happens, this state is called "samaadhi", which will the the culmination of one's spiritual journey.