This essay investigates the language of 4Q300, one of the manuscripts of the 'Mysteries' composition from caves 1 and 4 (1Q27, 4Q299–300), for the way in which it participates in the 'prophetic-sapiential' dynamic of Qumran apocalypticism. Though 4Q300 may not have been authored by a member of the Qumran community, it expresses ideas and assumes social categories very much at home within a sectarian context. It presumes a dualistic framework in which the in-group possesses knowledge of 'mysteries' that derives from having access to a 'vision.' This vision is sealed to the opponents, the 'magicians' whose failed interpretations render them 'guilty' of not understanding the true 'root of wisdom.' The essay argues that this 'vision' is best understood to be a written source that is considered by the author/audience of 4Q300 to have prophetic implications.