The last eighteen verses of chapter two answer a question Arjuna asks almost as an aside: what does such a person look like, how do they speak, sit and walk? The reply is one of the most quoted passages in Indian literature and is recited daily in many households, often by people who could not summarise the philosophy that produces it.
The description is negative more often than positive. The person of settled understanding has put away the desires that arise in the mind and is satisfied in the self by the self. They are not agitated in trouble and not eager in pleasure. They draw the senses back from their objects as a tortoise draws in its limbs. They are awake in what is night for others, and what keeps others awake is night to them. Desires enter such a person as rivers enter the sea, which is filled and stays still, and not as rivers enter a pool, which floods.
What makes the passage durable is that none of it describes an achievement anyone can display. There is no posture, no rank, no visible mark. The chapter has just spent forty verses arguing that action cannot be avoided, and it closes by insisting that the difference between one actor and another is entirely interior. The final verses trace the opposite course with the same care, from dwelling on objects to attachment, from attachment to desire, from desire to anger, from anger to confusion, and from confusion to the loss of everything, which is the clearest short account of how a mind comes apart that the book contains.