Consciousness-only (vij˝apti-mātratā, vij˝apti-mātra, citta-mātra) is a theory according to which all existence is nothing but consciousness, and therefore there is nothing that lies outside of the mind.
This means that conscious-experience is nothing but false discriminations, imaginations; a provisional antidote; thus, the notion of consciousness-only is an indictment of the problems the activities of consciousness engender. This was a major component of the thought of the school of Yogācāra (瑜伽行派).
The Vij˝ānavādins explained the regularity and coherence of sense impressions as due to an underlying store of perceptions (ālaya-vij˝āna) (阿賴耶識) evolving from the accumulation of traces of earlier sense perceptions. These are active, and produce seeds (種子) similar to themselves, according to a regular pattern, as seeds produce plants. Each being possesses a store of perceptions and beings which are generically alike will produce similar perceptions from their stores at the same time. Its doctrine reduces all existence to one hundred dharmas (法 factors) in five divisions 五位, namely, mind, mental function, material, not associated with mind and unconditioned, dharmas.
According to this school, the external world is created when the ālaya (storehouse) consciousness is influenced ('perfumated') (薰) by "seeds" or effects of good and evil deeds.
Another important contribution of the Consciousness-only thinkers was that of the three natures of imaginary, provisional and real. See three natures 三性 for details.
The major framework of Yogācāra theory was developed by the two brothers Vasubandhu 世親 and Asaṅga 無著 in such treatises as the Abdhidharma-kośa-bhāsya 倶舍論, the Triṃśikā Vij˝aptimātratāsiddhiḥ (Thirty Verses on Consciousness-only) 唯識三十頌, Mahāyāna-saṃgraha攝大乘論, and the Yogācārabhūmi-śāstra瑜伽師地論.
Consciousness-only doctrine was also defined in sutras such as the Saṃdhinirmocana-sūtra and Śrīmālā-sūtra 勝鬘經. The Mahāyāna-saṃgraha, for example, says "All conscious objects are only constructs of consciousness because there are no external objects. They are like a dream" (如此衆識唯識 以無塵等故 譬如夢等) 〔攝大乘論T 1593.31.118b12 〕.