This monograph explores the relationship between language and conceptualization by means of an in depth corpus based and experimental investigation of the major types of expressions of epistemic modality in Dutch, German and English. By adopting a systematic functional orientation, the book explains a whole range of peculiarities of epistemic expression forms (synchronically and diachronically), and it offers a clear perspective on which cognitive systems are needed to get from the concept of epistemic modality to its linguistic expression. On that basis the author postulates a sophisticated, layered view of human conceptualization.