7. Nature, or prakriti, is the principle behind all things in the changing world. It is made up of three sub-principles or qualities (guna); all things in the material world are the product of the mixture of these qualities. All changes and all developments are the product of these qualities. Nature, like spirit or consciousness (purusha), is unchanging and eternal. Only the products or evolvents of nature change and devlop. The field, or Kshetra, is the result of the joining of consciousness and nature.