Moreover, that Mercury is the steward of the souls, and that on this account he has the name of Conductor, and Commercial, and Infernal, since it is he who conducts the souls from their bodies, and from earth, and sea; and that he conducts the pure souls to the highest region, and that he does not allow the impure ones to approach them, nor to come near one another; but commits them to be bound in indissoluble fetters by the Furies. The Pythagoreans also assert, that the whole air is full of souls, and that these are those which are accounted dæmones, and heroes. Also, that it is by them that dreams are sent among men, and also the tokens of disease and health; these last too, being sent not only to men, but to sheep also, and other cattle. Also, that it is they who are concerned with purifications, and expiations, and all kinds of divination, and oracular predictions, and things of that kind. They also say, that the most important privilege in man is, the being able to persuade his soul to either good or bad. — Diogenes Laertius, *Lives of Eminent Philosophers*, Book VIII, Section XIX, trans. C. D. Yonge (1853). **Surface Gloss:** Hermes sorts disembodied souls by purity, raising the pure to the upper ether while the lower atmosphere remains crowded with souls called *daimones* and heroes, who transmit dreams, omens of health or sickness, and divination to mortals and flocks. **Ambient Medium Hygiene:** Treat your surrounding information and social environment not as empty space, but as an "air crowded with daimones"—a dense, active medium constantly transmitting contagious moods, diagnostic signals, and false phantasms into your head. You cannot stop the medium from broadcasting, so you must regulate your "receiver" (diet, sleep threshold, evening wind-down) to filter signal from agitation.
— In our words · Source: Lives of Eminent Philosophers (Diogenes Laertius)