Plane of Transcendence
This Plane is defined by ideas and the perceptions of individuals rather than definitive matter. Within this Plane it does not matter so much exactly what something is, rather it only matters the idea of what it is. This idea is reinterpreted by the perceptions of all who sense it. For example, should a monster show up, one person may see a tiger while another sees a crocodile. Instead of what it actually is being important, the idea of a monster that is attacking you is what is prominent. All Ethereal races were born within this Plane. As such they speak the Universal Language. This language, instead of speaking actual words, conveys direct ideas to the mind of the subject. So while no other race has the ability to speak it, they innately understand it.