The original meaning of the word jhàna, Sanskrit dhyàna, was `to ponder' or `to ruminate' although by the Buddha's time it had come to mean any deep meditative attainment. The Buddha used the word jhàna for the stages the mind passes through as it progresses from cluttered normality to pristine clarity. Although he identified four such stages, they should not be thought of as being distinct and separate. Rather, one stage flows towards and is transformed into another as the various mental concomitants develop or fade.
The first step in attaining the jhànas is prolonged and disciplined meditation to the stage where the five hindrances are weakened or temporarily suspended. This gives rise to a state where there is `a distance from sense desires and unskilled states of mind' (vivicc'eva kàmehi vivicca akusalehi dhammehi), where thoughts continue (savitakkaü savicàraü) although they are much reduced and mainly neutral in content, and where there is a subtle but noticeable joy and happiness (pãti sukha). The meditator then `suffuses, utterly suffuses, fills and permeates' (abhisandeti, parisandeti, paripåreti, parippharati) his or her body with that joy and happiness. The Buddha called this the first jhàna.
If this state continues to be cultivated, thoughts eventually stop completely (avitakkaü avicaraü), the mind becomes effortlessly focused (cetaso ekodhibhàvaü), and one experiences a deep inner tranquillity (ajjhattaü sampasàdanaü) while continuing to suffuse the body with joy and happiness. This is called the second jhàna.
In time, joy fades away (pãtiyà ca viràgà), equanimity (upekkhà), crystal-clear mindfulness and awareness (satisampajà¤¤a) become pronounced and one experiences the happiness (sukha) that is usually only the privilege of enlightened ones. This is called the third jhàna.
In the fourth and highest jhàna one becomes completely detached from all physical and psychological pleasure and pain (sukhassa ca pahànà dukkhassa ca pahànà pubb'eva somanassa domanassànaü atthaïgamà) and the mind is emptied of everything except utterly pure equanimity and mindfulness (upekkhàsati pàrisuddhiü, D.I,73-75).
It will be noticed that the three main components of the jhànas are positive feeling, mindfulness and equanimity. The joy and happiness, which continues even after the meditator emerges from the jhànic state, helps to untie the emotional knots and psychological wounds of the past thus simplifying the mind and imparting a deep contentment. The mindfulness allows for a clear penetrating vision of things, while the equanimity keeps it from getting entangled in anything. The meditator becomes a still watching centre which is gradually filled with wisdom.