Like Plutarch Apuleius firmly believed in the existence of daemons. They populated the air and were in fact formed of air. They experienced emotions just like human beings, and their mind was rational. In a sense, then, the human soul was also a daemon, but there were daemons who never entered bodies.[62] In his treatise On Socrates' God Apuleius presented a complete, systematic version of daemonology that was acceptable to later Platonists.