What are the jhanas (meditative absorptions)? Are jhanas necessary for awakening?

A jhāna is a stable state of deep concentration in which the mind is collected and lets go, step by step, of the coarser components of experience. The canon describes four such jhānas and uses them to define right concentration (sammā-samādhi), the eighth factor of the path (SN 45.8).

The formula recurs throughout the canon, for instance in MN 39:

• First jhāna: secluded from sensual pleasures and unwholesome states, with applied and sustained thought (vitakka, vicāra), and with rapture (pīti) and pleasure (sukha) born of seclusion.
• Second: applied and sustained thought subside; there remain inner confidence, unification of mind, and pīti and sukha born of concentration.
• Third: rapture fades; equanimity (upekkhā), mindfulness, clear comprehension and sukha remain.
• Fourth: with joy and grief already gone, both pleasure and pain are abandoned; the state is neither painful nor pleasant, with purity of mindfulness due to equanimity.

So this is not a scale of increasing pleasure: by the fourth jhāna sukha has been given up and neutral feeling remains.

Beyond these come the four formless bases (arūpa-āyatana): infinite space, infinite consciousness, nothingness, neither-perception-nor-non-perception (MN 111). Later literature sometimes calls them formless jhānas, but the suttas keep a separate term for them, and describing them as a further increase of pīti and sukha is wrong: their standard formulas are defined by a shift in perception.

Entering jhāna is preceded by abandoning the five hindrances: sensual desire (kāmacchanda), ill will (byāpāda), dullness and drowsiness (thīna-middha), restlessness and remorse (uddhacca-kukkucca), and doubt (vicikicchā).

The suttas state no rule that you must master at least the first jhāna before taking up insight. They do define right concentration precisely as the four jhānas (SN 45.8), and they make jhāna a basis for the destruction of the taints: in AN 9.36 the practitioner regards the phenomena of the jhāna as impermanent, suffering and not-self. Commentarial Theravāda also allows a path of dry insight (sukkhavipassaka), in which mundane jhāna is not attained beforehand. These are different levels of description, and they are still read in different ways.

A jhāna remains a conditioned attainment - not nibbāna and no guarantee of liberation. In MN 111 Sāriputta goes through the jhānas and the formless bases, discerning their components one by one: these states, not having been, come to be; having been, they vanish. He is neither drawn to them nor repelled by them, and he sees that there is an escape beyond. Nor is the happiness of jhāna the highest available to a human being: MN 59 sets out a series of ever subtler kinds of happiness, in which the formless bases stand above the jhānas and the cessation of perception and feeling stands at the top.

Where to read: MN 39, MN 111, MN 59.