'consciousness', is one of the 5 groups of existence (aggregates; khandha); one of the 4 nutriments (āhāra); the 3rd link of the dependent origination (paticcasamuppāda); the 5th in the sixfold division of elements (dhātu).
Viewed as one of the 5 groups (khandha), it is inseparably linked with the 3 other mental groups (feeling, perception and formations) and furnishes the bare cognition of the object, while the other 3 contribute more specific functions. Its ethical and karmic character, and its greater or lesser degree of intensity and clarity, are chiefly determined by the mental formations associated with it.
Just like the other groups of existence, consciousness is a flux (viññāna-sotā, 'stream of c.') and does not constitute an abiding mind-substance; nor is it a transmigrating entity or soul. The 3 characteristics (s. ti-lakkhana), impermanence, suffering and no-self, are frequently applied to it in the texts (e.g., in the Anattalakkhana Sutta, S.XXII, 59). The Buddha often stressed that "apart from conditions, there is no arising of consciousness' (M 38); and all these statements about its nature hold good for the entire range of consciousness, be it "past, future or presently arisen, gross or subtle, in oneself or external, inferior or lofty, far or near" (S. XXII, 59).
According to the 6 senses it divides into 6 kinds, viz. eye- (or visual) consciousness (cakkhu-v.), etc. About the dependent arising of these 6 kinds of consciousness, Vis.M. XV, 39 says: 'Conditioned through the eye, the visible object, light and attention, eye-consciousness arises. Conditioned through the ear, the audible object, the ear-passage and attention, ear-consciousness arises. Conditioned, through the nose, the olfactive object, air and attention, nose-consciousness arises. Conditioned through the tongue, the gustative object, humidity and attention, tongue-consciousness arises. Conditioned through the body, bodily impression, the earth-element and attention, body-consciousness arises. Conditioned through the subconscious mind (bhavanga-mano), the mind-object and attention, mind-consciousness arises."
The Abhidhamma literature distinguishes 89 classes of consciousness, being either karmically wholesome, unwholesome or neutral, and belonging either to the sense-sphere, the fine-material or the immaterial sphere, or to supermundane consciousness. See Table I.