In reflecting on the imagery of nirvana, one must aspire simultaneously to (at least) two intellectual virtues: rigour and flexibility, while at the same time recognizing that there are limits, of various kinds, to what one can know. The historical philology of words can be productive of definite knowledge, and strict, close analysis of the words nirvāṇa/nibbāna, and of the various epithets, synonyms, verbs, etc., used in connection with them, is vital in clarifying the idea(s) they express; but at the same time, one must ask: how far can one know that people who use language are aware of the etymology of the words they use, or even if they are so aware, whether it matters to the way they are using them? The answer to such questions, I think, in language-users of whatever degree of education, is sometimes ‘yes’, sometimes ‘partially’, sometimes ‘not much, if at all’. In Buddhist traditions, as generally in South Asia, it was an accepted fact that there was one discipline, which corresponds to what the English word ‘grammar’ means (Sanskrit: vyākaraṇa; Pali: veyyākaraṇa, literally ‘explanation, elucidation, analysis’), that was astoundingly sophisticated and thoroughly rule-governed. At the same time, there was another discipline, practised by the same people and often at the same time, which is usually but very misleadingly called ‘folk etymology’ in modern academic works (Sanskrit: nirukti; Pali: nirutti), but which I prefer to call ‘creative etymologizing’.