Explore "Masters of Space" by E.E. Smith on Textopian. Read with annotations and highlights.
As has been said, the Stretts were working, with all the intensity of their monstrous but tremendously capable minds, upon their Great Plan; which was, basically, to conquer and either enslave or destroy every other intelligent race throughout all the length, breadth, and thickness of total space. To that end each individual Strett had to become invulnerable and immortal.
Wherefore, in the inconceivably remote past, there had been put into effect a program of selective breeding and of carefully-calculated treatments. It was mathematically certain that this program would result in a race of beings of pure force -- beings having no material constituents remaining whatever.