Kleshas are the structural deficiencies in human psychology. According to the Yogic philosophy, there are five kleshas, namely, Avidya (Ignorance), Asmita (Ego), Raga (Attachment), Dvesha (Aversion) and Abhinivesha (Selfishness). In Buddhist philosophy, the term Klesha is typically translated as "defilement" or "poison." In early Buddhist texts the kleshas were generally referred to mental states, which temporarily cloud the mind and manifest in unskillful actions. Over time the kleshas became depicted as "Three Poisons" that included greed, hatred, and delusion.
From the viewpoint of Yoga it is important to understand that emotional pain and its varied expressions, such as depression comes from the desire, attachment, fear and certain unconscious universal constructs, existing in all unliberated human minds. Kleshas or afflictions are thus five constructs or crystallised thought forms that are vividly described by Patanjali at the beginning of Sadhana Pada of the Yoga Sutra.
The Kleshas are described as follows -
Avidya Klesha - This Klesha occurs when the individual does not want to see the things as they are and they want to see the world as they want it to be like. It is the primal ignorance which pervades all of the creation. This ignorance is empirical, not conceptual, in nature. To individuals, avidya means that while the non-dual source of all existence and awareness is pure, all pervasive, immanent, and transcendent, searing from the core of the being. The individualised and unpurified sensory mind and the sense organs are relatively crude instruments compared to the subtlety of pure awareness that are incapable of directly perceiving it. The mind's higher nature or buddhi is capable of perceiving the radiant and blissful reflection of the Divine Self, but only when it has been sufficiently purified through determined practice. For most of the people, such purification requires many years of meditation practice, as well as the help of the teachers.
Asmita Klesha - People can have strong opinion about various things in life and they feel that their notions are right; this sense of strong opinion is the Asmita or Ego. As individuals have ahamkara or "I-maker" (ego), one is rotating in the single vritti or thought form with the idea of individualised existence. This single thought of a partial self is enormously convincing because it pervades the entire body-mind compound. It is the nature of this individual "I-am" sense, or ego, to identify with something and become inseparably attached to it. Since individuals do not easily perceive the existence of the Self, the ahamkara identifies with some sort of a limited self-concept, usually, the body-mind complex, social identity, individual attributes of personality or experience and so on. Individuals take birth into this world knowing only one thing: 'This body is mine'. But they fail to know the 'self' who is claiming the body. The result of this ignorance is the true nature and is, thus, the misidentification with some aspect of restricted existence, which is naturally painful because it is incomplete. Once this misidentification occurs, the whole perception of reality changes, so that the entire universe is divided into "me" versus "not-me" and the objects of the experience are divided into "mine" and "not-mine".
Raga Klesha - In life people are emotionally attached to many things. This is called 'Raga' or Attachment. However, because the identification of ahamkara was false to begin with, and because what is "me" is comparatively small to the large surrounding universe mostly composed on "not me", a kind of existential terror and uncertainty results. People do not want to face the overwhelming feeling of terror and they develop various strategies for distracting themselves from it for enlarging "me" and for strengthening and preserving the individual and continually threatening the small existence. This leads to the third klesha, raga or attraction, which creates a pattern of acquisition. People began to pursue human relationships, knowledge, wealth, status, power or anything, which might be capable of enlarging and protecting the fragile individualised existence. However, change is the nature of creation, all objects within it are temporary, and thus subject to loss at any moment.
Dvesha Klesha - This Klesha occurs when strong dislike arises for anything. In experiencing an object, which gives pleasure, one becomes attached to that pleasure, and desire to experience it once again. When the experience becomes unavailable to the individuals, they feel pain. Eventually the pain and anger turns to depression, helplessness, and finally hatred for the self and the world as well. Dvesha actually means "the hate which follows after experiencing the pain."
Abhinivehsa Klesha - This is the fear of life. Because of raga and dvesha, a tremendous, continual, and habitual outflowing of energy and attention through the senses to the objects of external world takes place. This outflow of all attention and energy can only increase the identification with the physical existence, making it even harder for the people to perceive or identify with their spiritual nature. Not only do people fear death because it represents an ending of the ability to fulfill our desires, but it also emotionally identifies with the body-mind complex and thus (at least subconsciously, if not consciously) believe that the existence will terminate with the death of the physical body. Abhinivesha means clinging to life, which "dominates even the wise."
The kleshas are embossed on 'chitta', the individual consciousness, from eternal passage of time and create and perpetuate the illusions that existence is limited to the mind-body complex. Even after death the 'chitta' retains the kleshas in seed form and they germinate to full culmination in the next incarnation. As long as the individual thinks that awareness is limited to the bodily existence, he lives forever in the mercy of forces that are beyond his control. If any action is done under any of the five mentioned Kleshas, its effects have to be confronted by the individual. Once the Kleshas are viewed with a wide outlook and positive thought, they will disappear. Yama, Niyama, Asana, Pranayama, Prathyara, Dharana, Dhyana leads the mind toward the necessary purification to overcome the Kleshas. Kleshas are to satiate the desire of the intellect. The third ?loka of Patañjali's Yogas?tra (a Hindu text) explicitly explains Five Poisons.