I have been trying to study and learn about the kasinas and jhanas, and found the following explanation by Bhikkhu Bodhi to be very clear and in-depth. Rather than trying to put this into my own words, I felt it best to just share it here unedited. It’s a lot to take-in, but hopefully you and I can keep coming back to it for deeper understanding.
The eighth factor of the path is right concentration, in Pali samma samadhi. Concentration represents an intensification of a mental factor present in every state of consciousness. This factor, one-pointedness of mind (citt’ekaggata), has the function of unifying the other mental factors in the task of cognition. It is the factor responsible for the individuating aspect of consciousness, ensuring that every citta or act of mind remains centred on its object. At any given moment the mind must be cognizant of something — a sight, a sound, a smell, a taste, a touch, or a mental object. The factor of one-pointedness unifies the mind and its other concomitants in the task of cognizing the object, while it simultaneously exercises the function of centring all the constituents of the cognitive act on the object. One-pointedness of mind explains the fact that in any act of consciousness there is a central point of focus, towards which the entire objective datum points from its outer peripheries to its inner nucleus.
However, samadhi is only a particular kind of one-pointedness; it is not equivalent to one-pointedness in its entirety. A gourmet sitting down to a meal, an assassin about to slay his victim, a soldier on the battlefield — these all act with a concentrated mind, but their concentration cannot be characterized as samadhi. Samadhi is exclusively wholesome one-pointedness, the concentration in a wholesome state of mind. Even then its range is still narrower: it does not signify every form of wholesome concentration, but only the intensified concentration that results from a deliberate attempt to raise the mind to a higher, more purified level of awareness.
The commentaries define samadhi as the centring of the mind and mental factors rightly and evenly on an object. Samadhi, as wholesome concentration, collects together the ordinarily dispersed and dissipated stream of mental states to induce an inner unification. The two salient features of a concentrated mind are unbroken attentiveness to an object and the consequent tranquillity of the mental functions, qualities which distinguish it from the unconcentrated mind. The mind untrained in concentration moves in a scattered manner which the Buddha compares to the flapping about of a fish taken from the water and thrown onto dry land. It cannot stay fixed but rushes from idea to idea, from thought to thought, without inner control. Such a distracted mind is also a deluded mind. Overwhelmed by worries and concerns, a constant prey to the defilements, it sees things only in fragments, distorted by the ripples of random thoughts. But the mind that has been trained in concentration, in contrast, can remain focused on its object without distraction. This freedom from distraction further induces a softness and serenity which make the mind an effective instrument for penetration. Like a lake unruffled by any breeze, the concentrated mind is a faithful reflector that mirrors whatever is placed before it exactly as it is.
The Development of Concentration
Concentration can be developed through either of two methods — either as the goal of a system of practice directed expressly towards the attainment of deep concentration at the level of absorption or as the incidental accompaniment of the path intended to generate insight. The former method is called the development of serenity (samatha-bhavana), the second the development of insight (vipassana-bhavana). Both paths share certain preliminary requirements. For both, moral discipline must be purified, the various impediments must be severed, the meditator must seek out suitable instruction (preferrably from a personal teacher), and must resort to a dwelling conducive to practice. Once these preliminaries have been dispensed with, the meditator on the path of serenity has to obtain an object of meditation, something to be used as a focal point for developing concentration.
If the meditator has a qualified teacher, the teacher will probably assign him an object judged to be appropriate for his temperament. If he doesn’t have a teacher, he will have to select an object himself, perhaps after some experimentation. The meditation manuals collect the subjects of serenity meditation into a set of forty, called “places of work” (kammatthana) since they are the places where the meditator does the work of practice. The forty may be listed as follows:
ten unattractive objects (dasa asubha)
ten recollections (dasa anussatiyo)
four sublime states (cattaro brahmavihara)
four immaterial states (cattaro aruppa)
one perception (eka sanna)
one analysis (eka vavatthana).
The kasinas are devices representing certain primordial qualities. Four represent the primary elements — the earth, water, fire, and air kasinas; four represent colours — the blue, yellow, red, and white kasinas; the other two are the light and the space kasinas. Each kasina is a concrete object representative of the universal quality it signifies. Thus an earth kasina would be a circular disk filled with clay. To develop concentration on the earth kasina the meditator sets the disk in front of him, fixes his gaze on it, and contemplates “earth, earth.” A similar method is used for the other kasinas, with appropriate changes to fit the case.
The ten “unattractive objects” are corpses in different stages of decomposition. This subject appears similar to the contemplation of bodily decay in the mindfulness of the body, and in fact in olden times the cremation ground was recommended as the most appropriate place for both. But the two meditations differ in emphasis. In the mindfulness exercise stress falls on the application of reflective thought, the sight of the decaying corpse serving as a stimulus for consideration of one’s own eventual death and disintegration. In this exercise the use of reflective thought is discouraged. The stress instead falls on one-pointed mental fixation on the object, the less thought the better.
The ten recollections form a miscellaneous collection. The first three are devotional meditations on the qualities of the Triple Gem — the Buddha, the Dhamma, and the Sangha; they use as their basis standard formulas that have come down in the Suttas. The next three recollections also rely on ancient formulas: the meditations on morality, generosity, and the potential for divine-like qualities in oneself. Then come mindfulness of death, the contemplation of the unattractive nature of the body, mindfulness of breathing, and lastly, the recollection of peace, a discursive meditation on Nibbana.
The four sublime states or “divine abodes” are the outwardly directed social attitudes — lovingkindness, compassion, sympathetic joy, and equanimity — developed into universal radiations which are gradually extended in range until they encompass all living beings. The four immaterial states are the objective bases for certain deep levels of absorption: the base of infinite space, the base of infinite consciousness, the base of nothingness, and the base of neither-perception-nor-non-perception. These become accessible as objects only to those who are already adept in concentration. The “one perception” is the perception of the repulsiveness of food, a discursive topic intended to reduce attachment to the pleasures of the palate. The “one analysis” is the contemplation of the body in terms of the four primary elements, already discussed in the chapter on right mindfulness.
When such a variety of meditation subjects is presented, the aspiring meditator without a teacher might be perplexed as to which to choose. The manuals divide the forty subjects according to their suitability for different personality types. Thus the unattractive objects and the contemplation of the parts of the body are judged to be most suitable for a lustful type, the meditation on lovingkindness to be best for a hating type, the meditation on the qualities of the Triple Gem to be most effective for a devotional type, etc. But for practical purposes the beginner in meditation can generally be advised to start with a simple subject that helps reduce discursive thinking. Mental distraction caused by restlessness and scattered thoughts is a common problem faced by persons of all different character types; thus a meditator of any temperament can benefit from a subject which promotes a slowing down and stilling of the thought process. The subject generally recommended for its effectiveness in clearing the mind of stray thoughts is mindfulness of breathing, which can therefore be suggested as the subject most suitable for beginners as well as veterans seeking a direct approach to deep concentration. Once the mind settles down and one’s thought patterns become easier to notice, one might then make use of other subjects to deal with special problems that arise: the meditation on lovingkindness may be used to counteract anger and ill will, mindfulness of the bodily parts to weaken sensual lust, the recollection of the Buddha to inspire faith and devotion, the meditation on death to arouse a sense of urgency. The ability to select the subject appropriate to the situation requires skill, but this skill evolves through practice, often through simple trial-and-error experimentation.
The Stages of Concentration
Concentration is not attained all at once but develops in stages. To enable our exposition to cover all the stages of concentration, we will consider the case of a meditator who follows the entire path of serenity meditation from start to finish, and who will make much faster progress than the typical meditator is likely to make.
After receiving his meditation subject from a teacher, or selecting it on his own, the meditator retires to a quiet place. There he assumes the correct meditation posture — the legs crossed comfortably, the upper part of the body held straight and erect, hands placed one above the other on the lap, the head kept steady, the mouth and eyes closed (unless a kasina or other visual object is used), the breath flowing naturally and regularly through the nostrils. He then focuses his mind on the object and tries to keep it there, fixed and alert. If the mind strays, he notices this quickly, catches it, and brings it back gently but firmly to the object, doing this over and over as often as is necessary. This initial stage is called preliminary concentration (parikkamma-samadhi) and the object the preliminary sign (parikkamma-nimitta).
Once the initial excitement subsides and the mind begins to settle into the practice, the five hindrances are likely to arise, bubbling up from the depths. Sometimes they appear as thoughts, sometimes as images, sometimes as obsessive emotions: surges of desire, anger and resentment, heaviness of mind, agitation, doubts. The hindrances pose a formidable barrier, but with patience and sustained effort they can be overcome. To conquer them the meditator will have to be adroit. At times, when a particular hindrance becomes strong, he may have to lay aside his primary subject of meditation and take up another subject expressly opposed to the hindrance. At other times he will have to persist with his primary subject despite the bumps along the road, bringing his mind back to it again and again.
As he goes on striving along the path of concentration, his exertion activates five mental factors which come to his aid. These factors are intermittently present in ordinary undirected consciousness, but there they lack a unifying bond and thus do not play any special role. However, when activated by the work of meditation, these five factors pick up power, link up with one another, and steer the mind towards samadhi, which they will govern as the “jhana factors,” the factors of absorption (jhananga). Stated in their usual order the five are: initial application of mind (vitakka), sustained application of mind (vicara), rapture (piti), happiness (sukha), and one-pointedness (ekaggata).
Initial application of mind does the work of directing the mind to the object. It takes the mind, lifts it up, and drives it into the object the way one drives a nail through a block of wood. This done, sustained application of mind anchors the mind on the object, keeping it there through its function of examination. To clarify the difference between these two factors, initial application is compared to the striking of a bell, sustained application to the bell’s reverberations. Rapture, the third factor, is the delight and joy that accompany a favourable interest in the object, while happiness, the fourth factor, is the pleasant feeling that accompanies successful concentration. Since rapture and happiness share similar qualities they tend to be confused with each other, but the two are not identical. The difference between them is illustrated by comparing rapture to the joy of a weary desert-farer who sees an oasis in the distance, happiness to his pleasure when drinking from the pond and resting in the shade. The fifth and final factor of absorption is one-pointedness, which has the pivotal function of unifying the mind on the object.
When concentration is developed, these five factors spring up and counteract the five hindrances. Each absorption factor opposes a particular hindrance. Initial application of mind, through its work of lifting the mind up to the object, counters dullness and drowsiness. Sustained application, by anchoring the mind on the object, drives away doubt. Rapture shuts out ill will, happiness excludes restlessness and worry, and one-pointedness counters sensual desire, the most alluring inducement to distraction. Thus, with the strengthening of the absorption factors, the hindrances fade out and subside. They are not yet eradicated — eradication can only be effected by wisdom, the third division of the path — but they have been reduced to a state of quiescence where they cannot disrupt the forward movement of concentration.
At the same time that the hindrances are being overpowered by the jhana factors inwardly, on the side of the object too certain changes are taking place. The original object of concentration, the preliminary sign, is a gross physical object; in the case of a kasina, it is a disk representing the chosen element or colour, in the case of mindfulness of breathing the touch sensation of the breath, etc. But with the strengthening of concentration the original object gives rise to another object called the “learning sign” (uggaha-nimitta). For a kasina this will be a mental image of the disk seen as clearly in the mind as the original object was with the eyes; for the breath it will be a reflex image arisen from the touch sensation of the air currents moving around the nostrils.
When the learning sign appears, the meditator leaves off the preliminary sign and fixes his attention on the new object. In due time still another object will emerge out of the learning sign. This object, called the “counterpart sign” (patibhaga-nimitta), is a purified mental image many times brighter and clearer than the learning sign. The learning sign is compared to the moon seen behind a cloud, the counterpart sign to the moon freed from the cloud. Simultaneously with the appearance of the counterpart sign, the five absorption factors suppress the five hindrances, and the mind enters the stage of concentration called upacara-samadhi, “access concentration.” Here, in access concentration, the mind is drawing close to absorption. It has entered the “neighbourhood” (a possible meaning of upacara) of absorption, but more work is still needed for it to become fully immersed in the object, the defining mark of absorption.
With further practice the factors of concentration gain in strength and bring the mind to absorption (appana-samadhi). Like access concentration, absorption takes the counterpart sign as object. The two stages of concentration are differentiated neither by the absence of the hindrances nor by the counterpart sign as object; these are common to both. What differentiates them is the strength of the jhana factors. In access concentration the jhana factors are present, but they lack strength and steadiness. Thus the mind in this stage is compared to a child who has just learned to walk: he takes a few steps, falls down, gets up, walks some more, and again falls down. But the mind in absorption is like a man who wants to walk: he just gets up and walks straight ahead without hesitation.
Concentration in the stage of absorption is divided into eight levels, each marked by greater depth, purity, and subtlety than its predecessor. The first four form a set called the four jhanas, a word best left untranslated for lack of a suitable equivalent, though it can be loosely rendered “meditative absorption.” The second four also form a set, the four immaterial states (aruppa). The eight have to be attained in progressive order, the achievement of any later level being dependent on the mastery of the immediately preceding level.
The four jhanas make up the usual textual definition of right concentration. Thus the Buddha says:
And what, monks, is right concentration? Herein, secluded from sense pleasures, secluded from unwholesome states, a monk enters and dwells in the first jhana, which is accompanied by initial and sustained application of mind and filled with rapture and happiness born of seclusion.
Then, with the subsiding of initial and sustained application of mind, by gaining inner confidence and mental unification, he enters and dwells in the second jhana, which is free from initial and sustained application but is filled with rapture and happiness born of concentration.
With the fading out of rapture, he dwells in equanimity, mindful and clearly comprehending; and he experiences in his own person that bliss of which the noble ones say: “Happily lives he who is equanimous and mindful” — thus he enters and dwells in the third jhana.
With the abandoning of pleasure and pain and with the previous disappearance of joy and grief, he enters and dwells in the fourth jhana, which has neither-pleasure-nor-pain and purity of mindfulness due to equanimity.
This, monks, is right concentration.
The jhanas are distinguished by way of their component factors. The first jhana is constituted by the original set of five absorption factors: initial application, sustained application, rapture, happiness, and one-pointedness. After attaining the first jhana the meditator is advised to master it. On the one hand he should not fall into complacency over his achievement and neglect sustained practice; on the other, he should not become over-confident and rush ahead to attain the next jhana. To master the jhana he should enter it repeatedly and perfect his skill in it, until he can attain it, remain in it, emerge from it, and review it without any trouble or difficulty.
After mastering the first jhana, the meditator then considers that his attainment has certain defects. Though the jhana is certainly far superior to ordinary sense consciousness, more peaceful and blissful, it still stands close to sense consciousness and is not far removed from the hindrances. Moreover, two of its factors, initial application and sustained application, appear in time to be rather coarse, not as refined as the other factors. Then the meditator renews his practice of concentration intent on overcoming initial and sustained application. When his faculties mature, these two factors subside and he enters the second jhana. This jhana contains only three component factors: rapture, happiness, and one-pointedness. It also contains a multiplicity of other constituents, the most prominent of which is confidence of mind.
In the second jhana the mind becomes more tranquil and more thoroughly unified, but when mastered even this state seems gross, as it includes rapture, an exhilarating factor that inclines to excitation. So the meditator sets out again on his course of training, this time resolved on overcoming rapture. When rapture fades out, he enters the third jhana. Here there are only two absorption factors, happiness and one-pointedness, while some other auxiliary states come into ascendency, most notably mindfulness, clear comprehension, and equanimity. But still, the meditator sees, this attainment is defective in that it contains the feeling of happiness, which is gross compared to neutral feeling, feeling that is neither pleasant not painful. Thus he strives to get beyond even the sublime happiness of the third jhana. When he succeeds, he enters the fourth jhana, which is defined by two factors — one-pointedness and neutral feeling — and has a special purity of mindfulness due to the high level of equanimity.
Beyond the four jhanas lie the four immaterial states, levels of absorption in which the mind transcends even the subtlest perception of visualized images still sometimes persisting in the jhanas. The immaterial states are attained, not by refining mental factors as are the jhanas, but by refining objects, by replacing a relatively gross object with a subtler one. The four attainments are named after their respective objects: the base of infinite space, the base of infinite consciousness, the base of nothingness, and the base of neither-perception-nor-non-perception. These states represent levels of concentration so subtle and remote as to elude clear verbal explanation. The last of the four stands at the apex of mental concentration; it is the absolute, maximum degree of unification possible for consciousness. But even so, these absorptions reached by the path of serenity meditation, as exalted as they are, still lack the wisdom of insight, and so are not yet sufficient for gaining deliverance.
The kinds of concentration discussed so far arise by fixing the mind upon a single object to the exclusion of other objects. But apart from these there is another kind of concentration which does not depend upon restricting the range of awareness. This is called “momentary concentration” (khanika-samadhi). To develop momentary concentration the meditator does not deliberately attempt to exclude the multiplicity of phenomena from his field of attention. Instead, he simply directs mindfulness to the changing states of mind and body, noting any phenomenon that presents itself; the task is to maintain a continuous awareness of whatever enters the range of perception, clinging to nothing. As he goes on with his noting, concentration becomes stronger moment after moment until it becomes established one-pointedly on the constantly changing stream of events. Despite the change in the object, the mental unification remains steady, and in time acquires a force capable of suppressing the hindrances to a degree equal to that of access concentration. This fluid, mobile concentration is developed by the practice of the four foundations of mindfulness, taken up along the path of insight; when sufficiently strong it issues in the breakthrough to the last stage of the path, the arising of wisdom.
May you be well, happy and peaceful.