Primary metaphors are tight conceptual pairings which arise directly from experience. For example, linguistic expressions like "burdened by grief" "heavy work load" etc. reflect the primary conceptual metaphor DIFFICULTIES ARE BURDENS, which links physical judgement of weight with subjective experiences such as discomfort, strain and effortfulness. The association between these concepts is explainable in terms of the recurring correlation in experience between the perception of heaviness and the subjective responses which accompany this perception. In this talk I will review some of the evidence for this special type of metaphorical conceptualization and discuss the nature of the concepts which are linked by primary metaphors. In particular, it appears that the Source concepts for primary metaphor are closely tied to perception and sensation (i.e. "image" in one sense of the term) while Target concepts are tied to our responses to these images -- including inferences, affective responses, and so forth. Given this relationship it seems that the images associated with primary metaphors could provide a great deal of the substance of conscious, subjective experience.