First Lensman by E.E. Smith

It has been said that the basic drive of the Eddorians was a lust for power; a thought which should be elucidated and perhaps slightly modified. Their warrings, their strifes, their internecine intrigues and connivings were inevitable because of the tremendousness and capability -- and the limitations -- of their minds. Not enough _could_ occur upon any one planet to keep such minds as theirs even partially occupied; and, unlike the Arisians, they could not satiate themselves in a static philosophical study of the infinite possibilities of the Cosmic All. They had to be _doing_ something; or, better yet, making other and lesser beings do things to make the physical universe conform to their idea of what a universe should be.

Their first care was to set up the various echelons of control. The second echelon, immediately below the Masters, was of course the most important, and after a survey of both galaxies they decided to give this high honor to the Ploorans. Ploor, as is now well known, was a planet of a sun so variable that all Plooran life had to undergo radical cyclical changes in physical form in order to live through the tremendous climatic changes involved in its every year. Physical form, however, meant nothing to the Eddorians. Since no other planet even remotely like theirs existed in this, our normal plenum, physiques like theirs would be impossible; and the Plooran mentality left very little to be desired.