Abstract According to Glaucus of Rhegium Democritus was “a disciple of a Pythagorean” (dk 68 A1, 38). The tetralogical catalog of his works prepared by Thrasylus begins its section on ethics with the three following works: Pythagoras; On the Disposition of the Wise Man; On the Things in Hades (dk 68 B0a–c). The very order of the first three ethical works of Democritus could point to some sort of dependence on Pythagoreanism. This was suggested earlier by Frank (1923: 67), who believes that this is due to the fact that Democritus saw Pythagoras as basically the founder of an ethic-religious sect. Without being forced to agree with Frank, it is undeniable that there are many similarities between Pythagorean and Democritean ethics. The Democritean sentences that speak about the sense of shame before oneself as a way of preventing evil deeds (dk 68 B84, 244, and 264) recalls the practice of anamnesis, the examination of conscience in the Pythagorean tradition. Even more important are the parallel uses of measure as a basis for ethical reasoning. This paper aims to review this connection between Pythagorean traditions and Democritus, examining what emerges as the most probable core issue to determine how close this relation between atomists and Pythagoreans could have been: the Aristotelian testimony (de An. 1.2 404a16-20 [dk 58 B40]) on the material conception of the Pythagorean soul. In fact, a corpuscular conception of the soul (“dust in the air”), foreshadowing the psychology of Democritus, is attributed to the Pythagoreans. Is the argument of de An. 1.2 404a16-20 a misunderstanding by Aristotle? Or does this testimony represent an actual dialogue that Pythagoreans were having with atomists in the fifth century bce?