No twentieth century work has inspired more metaphorical description than Edgard Varèse's 'Density 21.5'. Theorists have described it as having "energy," "impulse," "urge," and "climax"; as "holding back," "surging forward," "breaking out," and "shooting off in new directions." This paper will show how Mark Johnson's theory of embodied meaning provides a context within which it is possible not only to explain how the work translates metaphorically into motion, but to evaluate its coherence as a vehicle for metaphorical expression. 'Density 21.5' will be analyzed on the basis of the generic level metaphor MUSICAL EVENTS ARE ACTIONS. This metaphor is subject to elaboration through its entailments-inferences based upon our understanding of everyday actions. These allow us to explain musical events in terms of motion, goal-directedness, pathway, stability, force, counterforce, blockage, and containment. Questions that the analysis will address include: What constitutes a pathway of melodic motion? How are goals of motion defined? How is the success or lack of success of a particular musical action made clear to the listener? The analytical method works more satisfactorily for the first seventeen bars than for the work as a whole, suggesting that the metaphorical impulse that shaped Varèse's composition of this initial segment may have given way to more abstract procedures in the remainder. (Candace Brower)