'concentration'; lit. 'the (mental) state of being firmly fixed' (sam+ā+√ hā),
is the fixing of the mind on a single object.
"One-pointedness of mind (cittass' ekaggatā), Brother Visakha, this is called concentration" (M. 44).
Concentration - though often very weak - is one of the 7 mental concomitants inseparably associated with all consciousness. Cf. nāma, cetanā.
Right concentration (sammā-samādhi), as the last link of the 8-fold Path (s. magga), is defined as the 4 meditative absorptions (jhāna). In a wider sense, comprising also much weaker states of concentration, it is associated with all karmically wholesome (kusala) consciousness. Wrong concentration (micchā-samādhi) is concentration associated with all karmically unwholesome (akusala) consciousness. Wherever in the texts this term is not differentiated by 'right' or 'wrong', there 'right' concentration is meant .
In concentration one distinguishes 3 grades of intensity:
(1) 'Preparatory concentration' (parikamma-samādhi) existing at the beginning of the mental exercise.
(2) 'Neighbourhood concentration' (upacāra-samādhi), i.e. concentration 'approaching' but not yet attaining the 1st absorption (jhāna), which in certain mental exercises is marked by the appearance of the so-called 'counter-image' (patibhāga-nimitta).
(3) 'Attainment concentration' (appanā-samādhi), i.e. that concentration which is present during the absorptions. (App.)
Further details, s. bhāvana, Vis.M. III and Fund. IV.
Concentration connected with the 4 noble path-moments (magga), and fruition-moments (phala), is called supermundane (lokuttara), having Nibbāna as object. Any other concentration, even that of the sublimest absorptions is merely mundane (lokiya).
According to D.33, the development of concentration (samādhi-bhāvanā) may procure a 4-fold blessing:
(1) present happiness through the 4 absorptions;
(2) knowledge and vision (ñāna-dassana) - here probably identical with the 'divine eye' (s. abhiññā) through perception of light (kasina);
(3) mindfulness and clear comprehension through the clear knowledge of the arising, persisting and vanishing of feelings, perceptions and thoughts;
(4) extinction of all cankers (āsavakkhaya) through understanding the arising and passing away of the 5 groups forming the objects of clinging (s. khandha).
Concentration is one of the 7 factors of enlightenment (bojjhanga), one of the 5 spiritual faculties and powers (s. bala), and the last link of the 8-fold Path.
In the 3-fold division of the 8-fold Path (morality, concentration and wisdom), it is a collective name for the three last links of the path (s. sikkhā).