Upekṣā (Sanskrit; Pali: upekkhā), equanimity, impartiality, or imperturbability, is one of the central concepts of Buddhism. It refers to an absence of differentiation or preference.
Equanimity is a particular quality associated with wisdom, prajñā, which differs from indifference. Indifference is simply a sensation, vedanā, neither pleasant nor unpleasant. But equanimity is "moral quality": not a sensation but a volition, saṃskāra.
Upekṣā, as saṃskāra, is described as one of the factors of extremely developed concentration: the fourth Dhyāna, regardless of the object that will have achieved this concentration.
Upekṣā can be taken as the object of an exercise in concentration or a state to be attained and is then one of the Four Incommensurables. It is also the tenth pāramitā.
"The knowledge of equanimity toward mental formations," saṅkhārupekkhā-ñāṇa, is, according to the description of seven purities one of the stages of vipassanā practice.
Upekkhā-sambojjhaṅga is a factor of enlightenment, one of the seven qualities that enables one to attain nirvana.
According to Nyanaponika: "Equanimity is a perfect balance of the mind. In this state, rooted in a deep and penetrating vision of things, the mind is unshakeable. The second clear understanding on which equanimity must be based is the Buddha's teaching on non-self (anattā).
This doctrine shows that, at the level of ultimate reality, actions are not performed by a "person," nor does the result of those actions affect a "person," a "self. It also shows that, by way of consequence, if there is no "me", we cannot speak of "mine" either. It is the illusion of an 'I' that creates suffering and prevents or disturbs equanimity. "
There is a meditation on unlimited equanimity (upekṣapramāṇa); Philippe Cornu clarifies on this subject: "Equanimity should not be confused with apathetic indifference or simple neutrality. Impartiality here is a loving attitude that is no longer reserved for the few but intended for all.
The intention of such meditation is to get rid of aversion and attachment. Its object, all beings, is unlimited.
Alexis Lavis concurs, indicating that "This clarification is important, because this correlative disposition to tolerance (kṣānti), which Buddhist texts name upekṣā, is often translated as 'indifference, with the risk of seeing it as an attitude of contempt towards what does not interest me, whereas it is, as the Sanskrit term indicates, an overcoming (upa) of the egological expectations (ikṣa) that Buddhism considers to be illusorily added to experience. "