（citta-ma^tra）. "Consciousness-only （vijn~apti-ma^trata^）." The theory that all existence is nothing but consciousness， and therefore there is nothing that lies outside of the mind. Consciousness-only was a major component of the thought of the school of Yoga^ca^ra 瑜伽行派. The Vijn~a^nava^dins explained the regularity and coherence of sense impressions as due to an underlying store of perceptions （a^laya-vijn~a^na） 阿赖耶识 evolving from the accumulation of traces of earlier sense perceptions. These are active， and produce impressions 种子 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 elements （法 dharmas） into five divisions， namely， mind， mental function， material， not concomitant with mind and unconditioned， dharmas. According to this school， the external world is created when the a^laya （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.