Gurudev, in the Gita, Arjun asks Krishna about sthitapragnya. Does it mean being established in knowledge?
Correct, it means being stable. He described what sthitapragnya is;, the signs of sthitapragnya. It means being unwavered; whether you are poured with flooded with compliments or you are given umpteen numbers of insults; in both situations, if you keep your smile and equanimity, then you are called sthitapragnya.
Mahatma Gandhi used to listen to the second chapter of the Bhagavad Gita, everyday; where Krishna spoke about sthitapragnya. This was part of satsang.
When we were children, we had to learn this part of the chapter by heart; that is how one generation of children were brought up in this country.
This (second) chapter was significant because it gave the principles of how to keep the mind inward, balanced and at peace in adverse situations. There was so much emphasis on keeping that balance, whether it is an enemy or a friend, pleasant circumstances or unpleasant; not to hanker for praise or be hateful for any unpleasant comments or insults. Such ideas and concepts help manage ones mental and emotional state of mind.