Halliday & Matthiessen (1999: 233n):
Because of the vastness of lexis, we do not have a general description of lexical metaphorical domains within the overall ideation base. But it is possible to discern that a central resource for metaphor is human bodily experience; and that the human body itself, concrete phenomena located in space-time, and features of daily social life are the most favoured metaphorical motifs.