In a recent study entitled ‘Numinous Experience and Religious Language’, Dr Leon Schlamm has endorsed Rudolf Otto's well known and much discussed account of the relationship of religious experience to religious language, and then used this position to criticize some highly influential voices in the continuing debate on the precise nature of mystical experience. The aim of this paper, in response to Schlamm, is to question the plausibility of Otto's account in The Idea of the Holy of the nature of religious knowledge and his closely related understanding of the relationship between religious experience (or as he prefers, numinous experience) and religious language. By implication, this also calls into question Schlamm's use of Otto's position in his criticism of those writers on mysticism that he takes issue with, chiefly Steven Katz and those who propose an essentially Kantian interpretation of mysticism. However, for the most part I shall leave the contemporary debate on mysticism unaddressed, though my comments do have a bearing on it. If there is a wider target, it is chiefly those interpreters of religion, like Schlamm, who conceive of the relationship of religious experience (or the religious object itself) and religious language in essentially the same way as Otto. One thinks immediately here of Friedrich Schleiermacher, whom Otto admired greatly, and who stands in the same Liberal Protestant tradition. Also Karl Barth, who ironically, for all his strictures of Liberal Protestantism, actually propounded a view of the meaning and nature of religious language which is remarkably similar to the views of both Schleiermacher and Otto; at least at the beginning of his theological career, in his famous commentary on Romans: all that talk of God as ‘the inexpressible’ and ‘the Wholly Other’. In addition one could mention those classical texts of Hinduism and Buddhism, which like many contemporary writers on mysticism (e.g. the late Deirdre Green), conceive of mystical experience and the truth which it reveals as ‘beyond the scope of discursive thought, language and empirical activity’.