Reliably extracting knowledge by the direct method requires relatively deep language understanding, and consequently is far from a mature technology. Ide and Véronis (1994) provide a survey of early work on deriving knowledge from dictionary definitions, and the difficulties faced by that enterprise. For the most part knowledge obtained in this way to date has been either low in quantity or in quality (from an inference perspective). More recent work that shows promise is that of Moldovan and Rus (2001), aimed at interpreting WordNet glosses for nominal artifact concepts, and that of Allen et al. (2013), aimed at forming logical theories of small clusters of related verbs (e.g., sleeping, waking up, etc.) by interpreting their WordNet glosses.