49:2.24

6. The energizing types. Not all worlds are alike in the manner of taking in energy. Not all inhabited worlds have an atmospheric ocean suited to respiratory exchange of gases, such as is present on Urantia. During the earlier and the later stages of many planets, beings of your present order could not exist; and when the respiratory factors of a planet are very high or very low, but when all other prerequisites to intelligent life are adequate, the Life Carriers often establish on such worlds a modified form of mortal existence, beings who are competent to effect their life-process exchanges directly by means of light-energy and the firsthand power transmutations of the Master Physical Controllers.