Between extended metaphor and allegory: is blending enough?

Allegory can both be related to and differentiated from extended, linguistic metaphor. From one point of view it is simply a super-extended metaphor; from another however it involves a shift from a consciously apprehended metaphorical blend to a consciously apprehended fictional situation. Understanding the nature of this shift involves the issue of blending. Although almost vacuous in its most general versions, if construed as a theory of specifically figurative forms of thought, blending theory does have content. There is as yet however no evidence from experimental psychology for the occurrence of blending. The only presently available evidence for this is the conscious sense of fusion associated with new, poetic metaphor and related phenomena. In Blake's 'A Poison Tree' an allegorical fiction emerges out of a blend whose setting up is prompted by an extended metaphor, which itself in turn emerges out of a conventional metaphor that, almost certainly, does not involve blending. The analysis of 'A Poison Tree' casts vivid light on the relations between blending, allegory and issues of ontology, truth and reference.