The article traces the genesis of soku, a particle elevated to the status of an operator of dialectical logic by Japanese philosophers of the Kyto school, to a translation problem that occurred when Buddhist thought spread from India to China. On the basis of the analysis of its most famous locus of occurrence, a passage in the Heart Sutra, it is shown how eva, a Sanskrit particle with the function of distinguishing between logical types of sentences, was transformed into a (...) modifier of identity statements and an indicator of the inability of language to express deep-level Buddhist insights exhaustively. (shrink)