(He who) remains equipoised in sorrow and happiness, rests firmly in oneself, considers a clod of earth, stone and a piece of gold with equal importance, is evenly disposed towards the desirable and detestable, poised (dhīram), accepting praise and blame alike;
Krishna brings in his pet concept of evenness and poise, emphasized abundantly right from the 2nd chapter. Samatva is the watchword of Bhagavad Gita and yoga alike!
Sukha and duhkha are the only two resultants of our interactional life and wakeful state. Our senses interacting with their objects repeatedly bring these about. Sukhaduhkha arrival and retreat are natural, inevitable. Duhkha brings sukha, and sukha fetches duhkha. What is there more preferable then in either?
When this kind of evaluation and enrichment embraces the mind, sukha-duhkhas lose their unsettling impact. And the seeker rises to a higher level of evenness and poise. The enrichment extends to all other dvandvas like desirable-undesirable, praise-blame, and also to substances like gold, earth and stone, each of which has its own place in Nature. What an ineffable effulgence, relief and fullness does this vision bestow!