In a well-known passage (Juv. 13 (7).473a15–474a24), Aristotle preserves a fragment of Empedocles’ poem dealing with respiration, in which the clepsydra is used as a model for breathing. Although there is a substantial literature on this subject, most scholars have focused on explaining Empedocles’ account of the mode of operation of the clepsydra as well as on assessing the extent to which Aristotle’s interpretation does justice to Empedocles’ fragment. What has received little attention is the fact that Aristotle begins his criticism of Empedocles by offering a specific counterproposal of his own, one that rests on the idea that the mechanism of respiration can be explained in a much clearer fashion through the analogy of a forge bellows. References to bellows are actually already traceable to Homer. At the same time, the bellows–lungs analogy continued to be used for centuries after Aristotle. The aim of this chapter is to provide an overview of the existing literary and archaeological evidence about bellows in Greek antiquity in order to build a complete picture of its function and hence clarify Aristotle’s theory of respiration.