There are primary consciousnesses and mental factors.
In any cognition there are always these two kinds of conscious phenomena, which share five congruent features (mtshungs-ldan lnga). They share a common (1) object (yul), (2) reliance (rten), (3) mental aspect (rnam-pa), (4) time (dus) and (5) natal source (rdzas).
In a bare visual cognition of a blue clay jug, you have both primary visual consciousness and such mental factors as distinguishing, feeling a level of happiness and so forth.  These all take the blue clay jug as their common object. They arise from the same focal condition.  They share a common dominating condition as well, for they all rely on the cognitive sensors of the photosensitive cells of your eyes.
 They take on the same aspect of the object, which appears somewhat like a mental hologram. For example, when you place a clear piece of glass over a blue cloth, the glass takes on the same blue aspect as the cloth. If placed on a yellow cloth, it would take on a yellow aspect, although the glass itself is neither blue nor yellow. A conscious phenomenon is like a clear piece of glass. Although it has no physical qualities of its own, it takes on whatever aspect of an object that appears to it and does that by giving rise to what is like a mental hologram of the object. In any specific moment of cognition, then, both the primary consciousness and all its attendant mental factors take on the same aspect of the object that appears as a mental hologram.
 They occur at the same time, although to be more precise they are not exactly simultaneous. And  they all arise from tendencies that are imputations on the mental continuum as their natal source, although not all from the same karmic tendency, which is the assertion in Chittamatra, but from their individual tendencies. The tendencies for all the factors in each cognition share the same slant (ris-mthun). That means that the primary consciousness and mental factors come from their tendencies in such a combination that they work harmoniously together within a single cognition. According to the Chittamatra explanation, the object of the cognition, as a mental hologram, also shares the same natal source as the ways of being aware of it do in the cognition of it.
Primary consciousness, the mind and consciousness are synonymous terms that are mutually inclusive. When divided, there are six types, from visual consciousness to mental consciousness.
With primary consciousness (sems), synonymous with the mind (yid) and consciousness (rnam-shes), you are aware simply of the essential nature (ngo-bo) of anything that can be validly cognized. The essential nature, here, refers to whether something is a sight, sound, smell, taste, tactile sensation or mental object. The six types accepted by the Sautrantikas are the visual, auditory, olfactory, gustatory, tactile and mental consciousnesses.
In addition, there are principal awarenesses (gtso-sems), which are clusters of a primary consciousness and specific mental factors. Bodhichitta, for example, is a principal awareness comprised of mental consciousness focused on one’s own not-yet-happening enlightenment, together with the intention to benefit all beings and the intention to attain this enlightenment in order best to be able to do so.
In some of the Chittamatra explanations, Buddha taught eight types of consciousness, adding foundation consciousness (kun-gzhi rnam-shes, Skt. alayavijnana) and deluded awareness (nyon-yid) to these six. The former cognizes all objects unclearly and with non-determining cognition and, as the basis for imputation for all tendencies, is the foundation for and accompanies all cognitions. It was unspecified by Buddha to be either constructive or destructive but takes on the ethical status of the cognition it accompanies. Foundation awareness is also the basis for imputation for the conventional “me,” a person. As such, it is the locus for the defining characteristics of both a consciousness and the conventional “me.” Deluded awareness is focused on foundational awareness and grasps at it to be established as the self to be refuted by the coarse or subtle selflessness of persons.
There are 51 mental factors, namely the five ever-functioning, the five object-ascertaining, the eleven constructive, the six root disturbing emotions and attitudes, the twenty auxiliary disturbing emotions and the four changeable.
With a mental factor, you are aware of distinctions and qualities in an object, the essential nature of which you simultaneously cognize with a primary consciousness. There are a great number of such factors, which have been condensed into various lists. This particular enumeration of 51 derives from A Compendium of Special Topics of Knowledge (mNgon-pa kun-btus, Skt. Abhidharmasamuccaya), a Chittamatra text by Asanga. Among the many items not specifically mentioned here are love and compassion, which obviously are also mental factors.
Feeling a level of happiness, distinguishing, urge, paying attention or taking to mind, and contacting awareness make five. Because these (always) come in the company of every (instance of) a principal awareness, they are called the five ever-functioning (mental factors).
 Feeling a level of happiness (tshor-ba) is the experience of happiness, unhappiness or neither or the two (neutral) in response to the way in which contacting awareness differentiates an object, as explained below. Feeling some level of happiness is how you experience the ripening of the aftermath of your karma and may be either upsetting (zang-zing) or non-upsetting (zang-zing med-pa) depending on whether you have clinging (sred-pa) for your tainted aggregates or you are totally absorbed in a state of yogic bare cognition.
 Distinguishing (‘du-shes) takes an uncommon characteristic feature of the appearing object of a conceptual or non-conceptual cognition and ascribes a conventional significance to it. In doing so, it differentiates the object from everything that it is not, particularly the background and other objects in the same cognitive field of the cognition, for instance your field of vision.
 An urge (sems-pa) is what causes your primary consciousness to face or move toward a potential object of cognition. In the Sautrantika tenet system, it is equivalent to karma (las, karmic impulse).  Taking to mind (yid-la byed-pa), or paying attention, engages the primary consciousness with an object in a certain way – with a certain degree of attentiveness and with a certain manner of consideration.  Contacting awareness (reg-pa) differentiates an object as pleasant, unpleasant or neutral, thus serving as the foundation for experiencing it with a matching feeling of some level of happiness
As the five ever-functioning mental factors (kun-‘gro lnga), they are part of every moment of cognition. Thus, whenever you know something, your distinguishing has singled it out from everything else around it, an urge has moved one of your types of consciousness toward it and taking to mind has engaged with it with some level of attention and has regarded it in some way, for instance as impermanent. Your contacting awareness has differentiated this object as pleasant, unpleasant or neutral and, in accord with this, feeling has experienced it with happiness, unhappiness or a neutral feeling. Moreover, your reflexive awareness has noted all these factors, allowing you afterwards to remember this moment of cognition.
Intention, firm conviction, mindfulness, mentally fixating and discriminating awareness make five. It is explained that because these ascertain (the mind’s) involvement with specific cognitive objects they are called five object-ascertaining (mental factors).
. Intention (‘dun-pa) is the motivation to obtain the object or to do something with the object once it is obtained.  Firm conviction (mos-pa) focuses on an object that has been ascertained to be like this and not like that and holds on to it in such a way that you cannot be dissuaded.  Mindfulness (dran-pa) keeps you from forgetting about and thus losing your mental hold on a specific object with which you are familiar. It refers to the conscious activity of remembering or being continually mindful of something, not the passive storage of impressions.
 Mentally fixating (ting-nge-‘dzin) is mental placement on a specific object of cognition for any length of time. When perfected it becomes absorbed concentration.  Discriminating awareness (shes-rab) analyses a particular object, discriminating between what is to be accepted or rejected and which actions are to be practiced or avoided. When perfected it becomes the discriminating awareness of the selflessness of persons, thus accepting the actual way in which all persons exist and rejecting false distorted notions that persons are established as existing in the manner of an atman.
These five are the five object-ascertaining mental factors (yul-nges lnga). They function to help you gain certainty about an object.
Believing a fact to be true, moral self-dignity, care for how one’s actions reflect on others, the three roots of what’s constructive – detachment, imperturbability and lack of naivety – perseverance, a sense of fitness, a caring attitude, equilibrium or serenity, and not being cruel (are the eleven constructive mental factors. Each is) constructive from the point of view of being either an opponent or by essential nature, congruence and so forth.
 Believing a fact to be true (dad-pa) focuses on an object that is true or existent and considers it to be true or existent. It may focus like this either based on reason or with an aspiration to achieve the object, such as some good quality, or it may believe it in such a way that it clears away disturbing emotions toward it.  Moral self-dignity (ngo-tsha) is the sense to refrain from destructive behavior because of concern for how it reflects on yourself. It is a sense of self-respect.  Care for how one’s actions reflect on others (khrel-yod) is the sense to refrain from destructive behavior because of concern for how it reflects on your family, community, teacher, or any group that you belong to.
 Detachment (ma-chags-pa) is a lack, to some degree, of longing desire for some worldly object.  Imperturbability (zhe-sdang med-pa) is not wishing to cause harm in response to your own or other’s suffering.  Lack of naivety (gti-mug med-pa) is an awareness of the details of behavioral cause and effect or how persons exist and acts as an opponent to naivety about them. These last three, as the basis for not engaging in destructive behavior, are the three roots for what is constructive.
 Perseverance (brtson-‘grus) is zestful vigor for being constructive. With it, you exert great effort in constructive behavior.  A sense of fitness (shin-sbyangs) is a sense of flexibility and serviceability of the mind and body while focused on an object. With it, you feel you can stay focused for as long as you wish. It becomes exhilarating when perfected with the attainment of a stilled and settled state of mind of shamatha (zhi-gnas).
 A caring attitude (bag-yod) causes you to stay focused on constructive objects, actions and goals and not lean toward negative ones. With it, you are careful about your state of mind and behavior.  Equilibrium (btang-snyoms) is a state of mind temporarily free from mental dullness and flightiness of mind and thus in a natural state of openness.  Not being cruel (rnam-par mi-‘tshe-ba) is not merely not wishing to harm others who are suffering, but in addition, having concern for their welfare and, with compassion (snying-rje), wishing them to be free from their suffering.
Of these eleven, all are opponents for specific destructive states of mind. Thus, believing a fact to be true is the opponent for disbelieving it, detachment for longing desire, imperturbability for hostility, and so forth. A sense of fitness, a caring attitude, and equanimity, however, become constructive by means of being congruent with, and thus sharing five things in common with other constructive states of mind. For instance, a caring attitude becomes constructive by means of it being present with detachment, perseverance and so forth. Lastly, except for a sense of fitness and equilibrium, the other nine are constructive by nature. These two exceptions are not necessarily always constructive, because they may also accompany destructive or deluded mental states, such as when feeling attachment for deep levels of concentration.
Longing desire, anger, arrogance, unawareness, (deluded) indecisive wavering and (deluded) outlooks are the six root disturbing emotions and attitudes. They are the main (factors) that bring one’s mental continuum to (a state of) disturbance.
 Longing desire (‘dod-chags) is the wish to acquire something impure and tainted, which it regards as being worthwhile and attractive.  Anger (khong-khro) is the generation of a pugnacious attitude toward any object of cognition, animate or inanimate, with the wish to get rid of it by causing it harm. When such anger is directed specifically toward another human being, this is called hostility (zhe-sdang).  Arrogance (nga-rgyal, pride) is a feeling of being unique and special, better than everyone else.
 Unawareness (ma-rig-pa, ignorance) is the bewilderment of not knowing behavioral cause and effect or the reality of how persons exist. It is the root of uncontrollably recurring rebirth, samsara. Included under this disturbing emotion is naivety (gti-mug), which is this same unawareness when it specifically accompanies destructive states of mind.  Deluded indecisive wavering fluctuates between two conclusions concerning the object of your cognition and is inclined toward the incorrect conclusion or is evenly balanced between a correct and an incorrect one, thus crippling you with indecision.
A disturbing emotion or attitude (nyon-rmongs) is defined as a mental factor that, when developed, causes you to lose peace of mind and self-control. These first five root ones are known as the five disturbing emotions without an outlook on life (lta-min nyon-rmongs). The sixth disturbing emotion or attitude is the set of five disturbing attitudes with an outlook on life (lta-ba nyon-rmongs-can), as follows:
 A deluded outlook toward a transitory network (‘jig-tshogs-la lta-ba, ‘jig-lta) latches on to some impermanent network from your five aggregates and interpolates (projects) on to it either “me” or “mine.” In other words, this is your mistaken view of who it is you think you are, your view of a concrete ego-identity. Your five aggregates are constantly changing; however, with this deluded outlook you single out certain aspects of your aggregates and identify them with your false “me” or as the possession of that false “me,” in other words as “mine.”  An extreme outlook (mthar-‘dzin-par lta-ba, mthar-lta) grasps at the network of aggregates that comprise your supposedly concrete ego-identity and clings to it as either permanent or as having no continuity after death.
 Holding a deluded outlook as supreme (lta-ba mchog-tu ‘dzin-pa) grasps at either one of the two above deluded outlooks and the network of aggregates on which it is aimed and holds them as the supreme view. Grasping at that which changes as being your concrete ego-identity and feeling that this is the type of person you will always be, you believe that if you act according to this personality you will attain liberation. For instance, with the first deluded outlook you identify yourself as someone young and strong. With the second, you feel that this is the way you will always be. With the third, then, you would feel that if you could always keep yourself physically fit and looking young and attractive, you will solve all your problems and never be unhappy.
 An outlook of holding deluded morality or conduct as supreme (tshul-khrims-dang brtul-zhigs mchog-tu ‘dzin-pa) grasps at some improper discipline or conduct as leading to liberation from suffering. With such a delusion, you would stand on one foot all day or sleep on a bed of nails and regard it as a true path to liberation.
 A distorted outlook (log-lta) grasps at something that is always true and is always the case and, repudiating it, considers it as being never true and never the case. Such a distorted outlook would be, for instance, to deny the law of cause and effect, to believe that there is no such thing as liberation from suffering, and so forth.
These, then, are the root disturbing emotions and attitudes, the main things that delude your mind and bring you suffering.
Hatred, resentment, concealment of having acted improperly, outrage, envy, miserliness, pretension, concealment of shortcomings or hypocrisy, smugness or conceit, cruelty, no moral self-dignity, no care for how one’s actions reflect on others, foggy-mindedness, flightiness of mind, disbelieving a fact, laziness, not caring, forgetting, being unalert, and mental wandering make twenty. As these enhance, develop from and are proximate to the root disturbing emotions and attitudes, they are (called) auxiliary disturbing emotions.
 Hatred (khro-ba) is the harsh intention to cause harm to some other being. It is strong hostility, approaching violence.  Resentment (khon-‘dzin) is stubbornly holding a grudge from some harm done to yourself or your loved ones and seeking revenge.  Concealment of having acted improperly (‘chab-pa) is the devious attitude of attempting to hide from others the fact that you have committed a specific destructive act.  Outrage (‘tshigs-pa) is the residue of a strong feeling of hostility expressing itself in your intention to use harsh and abusive language.
 Envy (phrag-dog) is the inability to bear seeing or hearing about the good qualities or success of others.  Miserliness (ser-sna) clings to your possessions and, wanting them to last and increase, is unwilling to share them with others or even to use them yourself.  Pretention (sgyu) is claiming to possess qualities and abilities you do not have.  Concealment of shortcomings (g.yo, hypocrisy) is the ambitious and dishonest attitude of trying to gain advantage by hiding your faults from others.
 Smugness (rgyags-pa, conceit) is a puffed-up attitude of conceit and snobbery about your health, wealth and other worldly good qualities.  Cruelty (rnam-par ‘tshe-ba) is a total lack of feeling or consideration for others. It causes you to treat others as if they were inanimate objects, often with great maliciousness.  No moral self-dignity (ngo-tsha med-pa) is a lack of any sense to refrain from destructive behavior because of not caring about how it reflects on yourself.  No care for how your actions reflect on others (khrel-med) is a similar lack of any sense to refrain because of not caring about how your behavior reflects on others with whom you are associated, such as your family or teacher.
 Foggy-mindedness (rmugs-pa) is a state of mind in which your body feels weak and your mind works slowly. You are overcome with sluggishness and do not wish to do anything.  Flightiness of mind (rgod-pa) causes your attention to lose its hold on an object of cognition and to be drawn, uncontrollably, to another object, compelled by attachment or desire.  Disbelieving a fact (ma-dad-pa) is your disinclination to accept what is true and is the case.  Laziness (le-lo) is the disinclination to engage in something constructive because of clinging to something you consider more pleasurable.
 Not caring (bag-med) is not being careful to engage in constructive behavior or to refrain from destructive acts because of not taking behavioral cause and effect seriously. It is the opposite of a caring attitude.  Forgetfulness (brjed-nges) is losing an object of focus based on recalling something toward which you have a disturbing emotion or attitude.  Being unalert (shes-bzhin ma-yin-pa) causes you to enter into inappropriate behavior because of not discriminating correctly between what is proper and what is improper.  Mental wandering (rnam-par g.yeng-ba) is an attitude of restlessness motivated by any of the three poisons of longing desire, hostility or ignorance. With this, your mind is never steady, but always flitting from one object to the next.
As all these disturbing emotions derive from the six root ones, they are known as auxiliary disturbing emotions (nye-nyon).
Sleepiness or sleep, regret, gross detection and subtle discernment are the four changeable mental factors. They change over and again to become constructive, destructive or unspecified in accordance with the motivation they are congruent with.
 Sleepiness or sleep (gnyid) is a state of total sensory darkness in which your five types of sensory consciousness temporarily cease to function, leaving you only with mental cognition. Depending on your state of mind when falling asleep, such cognition will be constructive, destructive, or what has been unspecified by Buddha to be either.
 Regret (‘gyod-pa) is the wish not to repeat something that you did or made someone else do. Feeling badly about destructive deeds you have committed in the past and not wanting to repeat them is constructive. On the other hand, to feel this way about your constructive acts is destructive since it prevents you from enjoying their fruits.
 Gross detection (rtog-pa) investigates something roughly to get a general understanding of an object of cognition.  Subtle discernment (dpyod-pa) scrutinizes an object in detail to get a more precise understanding of it. How these last two mental factors are classified depends on whether the object you choose to understand is constructive, destructive or unspecified.
Thus, every cognition you have entails mental factors. Some are always present, neither beneficial nor detrimental. Some are constructive, others are not. By learning to discern which are the factors that are accompanying your bare cognitions, inferential cognitions and so forth, you can make all your cognitions constructive as well as valid.
Other Buddhist Theories
The Sautrantika division of (Svatantrika) Madhyamaka, Prasangika and Vaibhashika assert (only) three types of bare cognition: (1) sensory, (2) mental and (3) yogic bare cognition. They do not accept the bare cognition of reflexive awareness. However, Sautrantika, Chittamatra and the Yogachara division of (Svatantraka) Madhyamika insist on four: (1) sensory bare cognition, (2) mental bare cognition, (3) bare cognition of reflexive awareness and (4) yogic bare cognition.
The purpose of Buddha’s teaching many different theories, such as those concerning the mind and how it knows things, is to help lead limited beings to liberation and enlightenment. Although such explanations may seem contradictory at first, upon deeper contemplation it becomes evident that they are not. First, Buddha teaches a very rough, general description of how the mind works. When you have understood this much, then you are ready to comprehend further refinements and more precise descriptions.
If you wish to define something specifically and exactly, you use a conceptual isolate, a “nothing-other-than” – it is what is left over after you have excluded everything it is not. The more precise an explanation of the mind, then, the more you know what it is not. The more you know what it is not, the finer your understanding of what it is. Therefore, it is important to train yourself through the graded explanation of Buddha’s different tenet systems. from the Hinayana ones of the Vaibhashikas and Sautrantikas through the Mahayana ones culminating in the Madhyamaka-Prasangikas, in order to attain enlightenment for the sake of benefiting all limited beings.
One of the major points upon which further refinements are given is reflexive awareness – how it is that you experience what you do and later can remember it. A more precise understanding of the actual way in which all things exist leads to a finer appreciation of what it means for something to be an external object, or something that is no longer happening. Thus, there are further discussions of the focal conditions for bare cognition, what is subsequent cognition, what are the natures of objective and metaphysical entities, what is appearance, reality, deceptive cognition, deepest and superficial truths, explicit and implicit apprehensions, and so forth.
Another topic discussed is how karmic tendencies for future cognition are transmitted from lifetime to lifetime. In this context, foundation consciousness, the mental continuum and imputation are examined further. A finer understanding of selflessness leads to further refinements concerning yogic bare cognition and what it focuses on.
By following a path of learning how the mind works validly, you can come to understand how the omniscient mind of a Buddha knows everything. By hearing this, thinking about it and meditating upon it, you can develop such an omniscient mind yourself. Such training, then, is part of the pathway to enlightenment.
Because I feared this work might become too long, I have presented, more or less, only some basic lists. For specific examples of what has been defined, meanings to be understood and so on, please consult the general works (on Dharmakirti’s Commentary to [Dignaga’s “Compendium of] Validly Cognizing Minds”) as well as A Filigree of (Valid) Lines of Reasoning; (A Treatise Explanation of Dharmakirti’s “Commentary to [Dignaga’s ‘Compendium of] Validly Cognizing Minds’”) and so forth.
In order to (show) the hair-splitting differences concerning ways of knowing, which entail what should be accepted and rejected by those of subtle and aspiring intelligence, this brief compendium of jingles on ways of knowing has been compiled by someone named Lozang. By virtue of the effort made in this (work), may the eyes of all wandering beings be opened to see what is correct or defective. By following to its conclusion this excellent and unmistaken path, may everyone quickly attain the topmost achievement, omniscient (enlightenment).