Yliaster is the term coined by Paracelsus which refers to "Prime matter, consisting of body and soul". It is most likely a portmanteau of the Greek hyle (matter) and Latin astrum (star). To Paracelsus, the iliaster represented the two basic compounds of the cosmos, matter representing "below", and the stars representing "above". ... In this sense, the iliaster is the same as the prima materia. It is the formless base of all matter which is the raw material for the alchemical Great Work.