Abstract This article deals with two passages from the second book of Pliny the Elder’s Natural History, devoted to the topic of cosmic music. Pliny seems to reject a theory that was widely accepted in most contemporary sources as a commonplace. A close survey of these passages sheds some light on the reasons for Pliny’s scepticism: he looks well informed about the philosophical debate about the problems of acoustics that the theory raised as early as the time of Archytas, and his objections against the theory seem to refer to the early Pythagorean arguments reported by Aristotle in the treatise On the Heavens. Pliny’s position on cosmic harmony is also relevant for the understanding of his own cosmology and of his perspective on human knowledge, leading to a reconsideration of the role of sensory experience in his ‘scientific’ work.