Samatva or equanimity is the crux of the preachings of every enlightened soul that has ever roamed this planet. Words, languages and methods could vary but the message is to attain samatva. Any preaching or practice contrary to this is dogmatic.
In the context of the mind, it is the balance between the senses on one side and intellect (buddhi) on the other side. If one leans towards senses, one gets drenched in desires. When intellect dominates, one would be an aware person but might look down on others as they may lack compassion. That's why Krishna says that the best Yogi is he who feels for others, whether in grief or pleasure, even as he feels for himself (6.32). It's the coherence of awareness and compassion.
Krishna told us to treat things like gold and rock as the same; a cow, an elephant and a dog as the same. Later he told us to treat all people including friends and enemies as equals. Another way to understand this is that there are three different levels to treating people. One is like equality before law where two people have the right to be treated as equals. Second is like equating two persons or qualities where one is closer to our heart while another is not. It's treating parents and in-laws as equals. The third level is equating ourselves with others. Their sorrow is ours and our pleasure is theirs. It's pure compassion flowing out of samatva . Krishna calls this 'supreme bliss' which is attained when the mind is perfectly tranquil and passion is calmed. (6.27)
To achieve this, Krishna advises regular practice with determination (6.23). Even if the unsteady and restless mind wanders away, we need to bring it under control (6.26). He assures infinite bliss with this regular practice (6.28).
Source - Daily World