Occasionally metaphorical projections extend across utterances, using one or more utterances to set up a picture of the source domain that then needs to be connected to the target domain by cross-domain comparison. This projection may happen within the text itself, as in the popular science book by about a day in the life of the brain by Susan Greenfield. She sets up a systematic comparison between consciousness and a stone thrown into a pond and employs various extended comparisons across utterances across the book. It may also happen between the text as a whole, which is then a story or argument or exposition in the source-domain, on the one hand, and the context of the text that is to be supplied by the reader, on the other. An example is ‘The road not taken’ by Robert Frost, which on the surface is about a walk in the woods but metaphorically talks about making choices in life.

At utterance level, these are all deliberate metaphors that directly and exclusively refer to aspects of the source domain. At the level of discourse, these are all discourse units that set up a story or argument in the source domain, which are related to each other by means of narrative or argumentative links. These elements and their links are then supposed to be transferrable to similar elements and links in the target domain. The comparison between the two domains does not take place within distinct utterances, but across utterances that serve as texts about two distinct domains before the overall mapping can be completed.

Such discourse structures require metaphorical thinking between two parallel text fragments or even complete texts. This may be of more extended duration than typically happens with metaphors that are not expressed at such textual elements, but as single words or phrases within utterances. This involves complex process of cognition which may also require slower and more voluntary thinking. The effect of this particular use of deliberate metaphor in comparison with more regular, limited metaphor is a key issue that is high on the agenda for structural and processing research in DMT.