The main question I wish to address in this chapter is the following: how can we account for metaphor variation in naturally occurring discourse using the cognitive linguistic theory of metaphor variation, as worked out in Kövecses (2005)? More specifically, what are the dimensions along which metaphors vary in natural discourse? Which aspects of metaphor are involved in this variation? And most importantly, what are the causes that produce such variation? In this chapter I propose a new notion in understanding the causes of metaphor variation in discourse: 'the pressure of coherence'. The notion provides us with an explanation of metaphor variation in discourse that has not been available previously. As Conceptual Metaphor Theory emphasizes (e.g. Grady 1997; Lakoff and Johnson 1999; Kövecses, 2002), many conceptual metaphors are universal at a high level of abstraction. I have argued elsewhere that conceptual metaphors vary along certain dimensions in relation to several aspects, or components, of these metaphors due to a number of different causes (Kövecses, 2005). This variation is especially noticeable at a 'culture-close' specific level of generalization. Equally obviously, conceptual metaphors vary across cultures. Somewhat less obviously, conceptual metaphors also vary within cultures. (Zoltán Kövecses)