A thought (cinta) is a discreet mental event sometimes also called ideation or cognition. Thoughts can take the form of mental pictures or as sub-vocal speech. A string or flow of thoughts is called thinking (cetana). Some of the different types of thinking include problem solving, reasoning, reflecting, remembering, assessing, introspecting, decision making, imagining, etc.
The Buddha classified thought processes as either logical thinking (vitakka) or wandering thinking (vicara). The first of these would be the deliberately sustained thinking that takes place during problem solving or reasoning, while day dreaming would be an example of the second. Thoughts and emotions are intimately connected, one often bringing forth the other. The Buddha gives as an example of this a man who thinks about some wrong he had done and then starts to feel guilty or depressed (M.II,165). He also recognized that deliberately thinking a certain type of thought often enough may result in the formation of a fixation and subsequent biases and prejudices. ‘Whatever one thinks about and ponders on (anuvitakka anuvicara) often the mind gets a leaning in that way’ (M.I,115). The mind (i.e. its thoughts) ‘precedes everything’ (Dhp.1), is ‘difficult to detect’, ‘very subtle’ ‘seizes whatever it wants’ (Dhp.36) and ‘thrashes about like a fish pulled out of the water’ (Dhp.34).
The Buddha's main interest in thinking concerned its power to distort reality, to trick us into seeing things that are not there and failing to see things that are, and to be ‘carried away’ by thoughts. In his famous Madhupindika Sutta he analyzed the process of cognition, starting with sensory contact (i.e. seeing, hearing, tasting, etc), ‘with sensory contact as cause feeling arises, what one feels one perceives, what one perceives one thinks about, what one thinks about one mentally proliferates. This mental proliferation (papanca), tinged with perceptions and concepts, obsesses a person in respect to the past, present and future’ (M.I,111-2). Thus the Buddha said; ‘The world is led around by mind, by mind the world is plagued’ (S.I,39) One of the preliminary goals of meditation is to slow down or if possible to stop the thought process so that the mind becomes more spacious and more quiet and rested. In the Vitakkasanthana Sutta the Buddha recommended five techniques for achieving this (M.I,119.ff). Mindfulness of breathing can also help with this. The Buddha said; ‘This concentration on in-and-out breathing, if cultivated and developed, is something peaceful and excellent, something perfect in itself and a pleasant way of living also. More than that, it dispels evil thoughts that have arisen and makes them vanish in a moment. It is just as when, in the last month of the hot season, the dust and dirt fly up and suddenly a great shower of rain lays it and makes it settle in a moment’ (S.V,321). In insight meditation one trains oneself to observe thoughts without reacting to them, or as the Buddha put it ‘in the cognized let there be just the cognized’ (vinnate vinnatamatttam, Ud.8). If this can be done the power of thoughts to enchant and mislead is minimized.