Kleshas (Sanskrit: क्लेश, romanized: kleśa; Pali: किलेस kilesa; Standard Tibetan: ཉོན་མོངས། nyon mongs), in Buddhism, are mental states that cloud the mind and manifest in unwholesome actions. Kleshas include states of mind such as anxiety, fear, anger, jealousy, desire, depression, etc. Contemporary translators use a variety of English words to translate the term kleshas, such as: afflictions, defilements, destructive emotions, disturbing emotions, negative emotions, mind poisons, neurosis etc.
In the contemporary Mahayana and Theravada Buddhist traditions, the three kleshas of ignorance, attachment, and aversion are identified as the root or source of all other kleshas. These are referred to as the three poisons in the Mahayana tradition, or as the three unwholesome roots in the Theravada tradition.
While the early Buddhist texts of the Pali canon do not specifically enumerate the three root kleshas, over time the three poisons (and the kleshas generally) came to be seen as the very roots of samsaric existence.
In the Pali Canon's discourses (sutta), kilesa is often associated with the various passions that defile bodily and mental states. In the Pali Canon's Abhidhamma and post-canonical Pali literature, ten defilements are identified, the first three of which – greed, hate, delusion – are considered to be the "roots" of suffering.
For instance, the Samyutta Nikaya includes a collection of ten discourses (SN 27, Kilesa-saṃyutta) that state that any association of "desire-passion" (chanda-rāgo) with the body or mind is a "defilement of mind" (cittasse'so upakkileso):
More broadly, the five hindrances – sensual desire (kāmacchanda), anger (byāpāda), sloth-torpor (thīna-middha), restlessness-worry (uddhacca-kukkucca), and doubt (vicikicchā) – are frequently associated with kilesa in the following (or a similar) manner:
While the Sutta Pitaka does not offer a list of kilesa, the Abhidhamma Pitaka's Dhammasangani (Dhs. 1229ff.) and Vibhanga (Vbh. XII) as well as in the post-canonical Visuddhimagga (Vsm. XXII 49, 65) enumerate ten defilements (dasa kilesa-vatthūni) as follows:
The Vibhanga also includes an eightfold list (aṭṭha kilesa-vatthūni) composed of the first eight of the above ten.
Throughout Pali literature, the first three kilesa in the above tenfold Abhidhamma list (lobha dosa moha) are known as the "unwholesome roots" (akusala-mūla or the root of akusala); and, their opposites (alobha adosa amoha) are the three "wholesome roots" (kusala-mūla or the root of kusala). The presence of such a wholesome or unwholesome root during a mental, verbal or bodily action conditions future states of consciousness and associated mental factors (see Karma).
In the 5th-century CE commentarial Visuddhimagga, in its discussion of "Dependent Origination" (Pali: paticca-samuppada) (Vsm. XVII), it presents different expository methods for understanding this teaching's twelve factors (nidana). One method (Vsm. XVII, 298) divides the twelve factors into three "rounds" (vaṭṭa):
In this framework (see Figure to the right, starting from the bottom of the Figure), kilesa ("ignorance") conditions kamma ("formations") which conditions results ("consciousness" through "feelings") which in turn condition kilesa ("craving" and "clinging") which condition kamma ("becoming") and so on. Buddhaghosa (Vsm. XVII, 298) concludes:
As can be seen, in this framework, the round of defilements consists of:
Elsewhere in the Visuddhimagga (Vsm. XXII, 88), in the context of the four noble persons (ariya-puggala, see Four stages of enlightenment), the text refers to a precursor to the attainment of nibbana as being the complete eradication of "the defilements that are the root of the round" (vaṭṭa-mūla-kilesā).
The three kleshas of ignorance, attachment and aversion are referred to as the three poisons (Skt. triviṣa) in the Mahayana tradition and as the three unwholesome roots (Pāli, akusala-mūla; Skt. akuśala-mūla ) in the Therevada tradition. These three poisons (or unwholesome roots) are considered to be the root of all the other kleshas.
In the Mahayana tradition, the five main kleshas are referred to as the five poisons (Sanskrit: pañca kleśaviṣa; Tibetan-Wylie: dug lnga).
The Mahayana Mahaparinirvana Sutra lists approximately 50 kleshas, including those of attachment, aversion, stupidity, jealousy, pride, heedlessness, haughtiness, ill-will, quarrelsomeness, wrong livelihood, deceit, consorting with immoral friends, attachment to pleasure, to sleep, to eating, and to yawning; delighting in excessive talking and uttering lies, as well as thoughts of harm.
Mahayana literature often features an enumeration of "two obscurations" (Wylie: sgrib gnyis), the "obscuration of conflicting emotions" (Sanskrit: kleśa-avaraṇa, Wylie: nyon-mongs-pa'i sgrib-ma) and the "obscuration concerning the knowable" (Sanskrit: jñeya-avaraṇa, Wylie: shes-bya'i sgrib-ma).
Contemporary translators have used many different English words to translate the term kleshas, such as: afflictions, passions, destructive emotions, disturbing emotions, etc.
The following table provides brief descriptions of the term kleshas given by various contemporary Buddhist teachers and scholars:
All Buddhist schools teach that through Tranquility (Samatha) meditation the kilesas are pacified, though not eradicated, and through Insight (Vipassana) the true nature of the kilesas and the mind itself is understood. When the empty nature of the Self and the Mind is fully understood, there is no longer a root for the disturbing emotions to be attached to, and the disturbing emotions lose their power to distract the mind.