The characteristic of citta is cognizing an object and thus, every citta which arises must have an object. There is no citta without an object and each citta can know only one object at a time. Ekaggata is the cetasika which has as function to focus on that one object. Seeing-consciousness, for example, can only know visible object, it cannot know any other object and ekaggata focuses on visible object. Hearing-consciousness can only know sound it cannot know visible object or any other object and ekaggata focuses on sound.

     The word 'object' ( arammana) as it is used in the Abhidhamma does not have the same meaning as the word 'object' or 'thing' we use in common language. in common language we may call a thing such as a vase an object. We may think that we can see a vase, touch it and know that it is a vase all at the same time. In reality there are different cittas which know different 'ofject' (arammanas) through their appropriate doorways. These cittas rise one at a time and know only one object at a time. The citta which sees knows only visible object, it cannot know tactile object or a concept. Visible object is that which is experienced through the eyes. What is seen cannot be touched. We may understand this in theory, but the truth should be verified by being mindful of different objects which appear one at a time. 

     When we speak about an arammana, an object, we have to specify which kind of arammana. There is visible object which is known through the eye-door. There is sound which is known through the ear-door. Smell, tasteand tactile object are known through their appropriate sense-doors. Through the mind-door all these objects can be known as well. Everything which is real and also concepts and ideas, which are not real in the absolute sense, can be known through the mind-door. Thus we see that the word 'object' in the Abhidhamma has a very precise meaning. 

     Ekaggata which has as function to focus on an object is translated as 'one-pointedness' or concentration. when we hear the word concentration we may believe that ekaggata only occur in samatha, tranquil meditation, but this is not so. It is true that when calm is developed ekaggata also develops, but ekaggata does not only occur in samatha. Ekaggata accompanies every citta, although its quality is different as it arises with different cittas. Even when we are, as we call it in common language, 'distracted', there is ekaggata arising with the akusala citta since it arises with every citta. It focuses on the object which is cognized at that moment. For example, when there is moha-mula-citta (citta rooted in ignorance) accompanied by uddhacca (restlessness), there is also ekaggata cetasika accompanying that citta. There is ekaggata arising with all types of akusala citta. when we enjoy a beautiful sight or pleasant music there is ekaggata cetasika with the lobha-mula-citta. At that moment we are absorbed in the pleasant object and enslaved to it. There is concentration when one performs ill deeds. 

     Ekaggata which accompanies akusala ciata is also called 'miccha-samadhi', wrong concentration. Ekaggata which accompanies kusala citta is also called 'samma-samadhi', right concentration. Samadhi is another word for ekaggata cetasika. Although wrong concentration and right concentration are both ekaggata cetasika their qualities are different. Samma-samadhi focuses on the object in the right way, the wholesome way. There are many levels of right concentration.

      The Atthasalini (1, Part IV, Chapter1. 118, 119) states about ekaggata, and here it deals actually with samma-samadhi (1 see also Dhammasangani 11.) : 

This concentration, known as one-pointedness of mind, has non scattering (of itself) or non-distraction (of associated states) as characteristic, the welding together of the coexistent states as function, as water kneads bath-powder into a paste, and peace of mind or knowledge as manifestation. For it has been said: 'He who is concentrated knows, sees according to the truth.' ltis distinguished by having ease (sukha) (usually) as proximate cause (2 Pleasant feeling, is a jhana-factor aising only in four stages of rupa-jhana. It supports samadhi focusing on the meditation subject. In the highest stage of rupa-jhana pleasant feeling is abandoned and indifferent feeling accompanies the jhana-citta instead.) Like the steadiness of a lamp in the absence of wind, so should steadfastness of mind be understood. 

     Samma-samdhi is one of the jhana-factor which are developed in samatha in order to suppress the hindrances and attain jhaha (1 see Abhidhamma in Daily Life chapter 22.). The jhana factors of applied thought (vitakka), sustained thought (vicara), enthusiasm (piti), happy feeling (sukha) and samadhi have to be developed together in order to attain jhana. All the jhana-factors assist the citta to attain tranquillity by means of a
meditation subject.

     Some  people take wrong concentration for right concentration of samatha. They want to try to concentrate on one point with the desire to become relaxed. Then there is akusala citta with clinging to relaxation. The aim of samatha is not what we mean by the word 'relaxation' in common language, but it it the temporary elimination of defilements. In order to develop samatha in the right way, right understanding of its development is indispensable. Right understanding should know precisely when the citta is kusala citta and when akusala citta and it should know the characteristic of calm so that it can be developed. There are different stages of calm and as calm becomes stronger, samadhi also develops (2 In the beginning stage af calm there is still preparatory concentration (parikamma-samadhi) (Vis. IV, 31-33). When calm has reached the degree that it is approaching jhana there is access-concencration (upacara-samadhi). When jhana has been attained there is at that moment samadhi which is attainment-concentration (appana-samadhi). Ekaggata cetasika which accompanies rupavacara citta (rupa-jhanacitta) is altogether different from ekaggata arising with kamavacara citta, citta of the sense-sphere. In each of the higher stages of jhana there is a higher degree of calm and thus ekaggata becomes more refined. Ekaggata which accompanies arupavacara citta is different again: it is more tranquil and more refined than ekaggata arising with rupavacara citta.

     There is also samma-samadhi of vipassana. As we have seen, the second manifestation of ekaggata cetasika or samadhi mentioned by the Atthasalini is knowledge or wisdom. When panna knows a nama or a rupa as it is, there is at that moment also right concentration performing its function. Samma-samadhi is one of the factors of the eightfold Path. When panna knows, for example, the visible object which presents itself as only a rupa appearing through the eyes or the seeing which presents itself as only a nama which experiences visible object, there is also right concentration at that moment: samma samadhi focuses on the object in the right way. When samma-samadhi accompanies lokuttara citta, samma-samadhi is also lokuttara and it focuses on nibbana. Then samma-samadhi is a factor of the supramundane eightfold Path (lokuttara magga).

     Some people believe that in the development of vipassana they should try to focus on particular namas and rupas in order to know them as they are. If concentration accompanies a citta with desire for result it is wrong concentration. So long as one has not become a sotapanna (the person who has attained the first stage of enlightenment) the inclination to wrong practice has not been eradicated. We may still be led by desire and then we are on the wrong way. When a nama or rupa appears through one of the six doors there can be mindfulness of it and then, at that moment, right understanding of that reality can be developed. Right understanding is accompanied by right concentration which has arisen because of the appropriate conditions and which performs its function without the need to think of focusing on a particular object. Minifulness, right understanding and right concentration are realities which arise because of their own conditions, they are anatta. There is no self who can direct the arising of any citta or who can regulate the experiencing of a particular object. But the conditions for right mindfulness and right understanding can be cultivated; they are: studying the tealities the Buddha taught and considering them when they appear in daily life. 

     In the Gradual Sayings (Book of the Fours, Chapter V, 1, Concentration) we read about four ways of developing concentration. As to the first way, the Buddha explained that this is the development of the four stages of jhana which leads to 'happy living' in this life. As to the second kind, this is the concentration on 'consciousness of light' which is a meditation subject of samatha. This leads to 'knowledge and insight which means in this context, according to the commentary (Manorathapurani), clairvoyance. 

      As regards the third way of developing concentration, this leads, if developed and made much of, to 'mindfuIness and well-awareness'. We read: 

Herein, monks, the feelings which arise in a monk are evident to him, the feelings which abide with him are evident to him, the feelings which come to an end in him are evident to him. The perceptions which arise in him... the trains of thought which arise in him, which abide with him, which come to an end in him are evident to him. This monks, is called 'the making-concentration-to-become which conduces to mindfulness and well-awareness'.

And what sort of making-concentration-to-become, if developed and made much of conduces to the destruction of the asavas? Herein a monk dwells observing the rise and fall in the five khandhas of grasping, thus: Such is rupa, such is the arising of rupa, such its vanishing... Such is feeling...such is perception...such are the activities...Such is consciousness, such is the arising of consciousness, such the vanishing of consciousness. This, monks, is called 'the making-concentration-to-become which conduces to the destruction of the asavas'. There are the four forms of it. Moreover, in this connection I thus spoke in 'The Chapter on the Goal' in (the sutta called) 'The Questions of Punnaka'.

By searching in the world things high and low, 
He who has naught to stir him in the world, 
Calm and unclouded, cheerful, freed of longing.
He has crossed over birth and old age, I say.

I Are ekaggata and samadhi the same cetasika?
II Can there be samddhi with akusala citta?
III What is the difference between samma-samadhi in samatha and samma-samadhi in vipassana?
IV If we try to concentrate on sound is that the way to know sound as it is?