Don't get me wrong. I love Jack Vance. But usually the delight of reading his books comes from his use of language, his dry wit, his engaging stories, and the prodigious imagination he harnesses in the development of his favorite theme: cultural diversity--or rather, his rueful fascination with the human propensity for splintering into a myriad of diverse, mutually antagonistic cultures, each with their own convoluted and apparently arbitrary values, customs, laws, rituals, hierarchies, and religions. In a sense, you could say that Vance's science fiction, isn't really science fiction; for in lieu of extrapolating the effects of future science and technology on man and society, he writes assuming that man's nature is fixed. Thus, except for being premised on the existence of spaceships that (somehow) have allowed man to spread to the stars, Vance ignores science in his novels of the future, choosing instead to exercise his imagination in extrapolations of the ever-more bizarre and disparate cultures he feels it is man's nature to divide into given the lebensraum in which to manifest his perversity.
This book's different though. Instead of his cynically detached storytelling, here we have the explication of social theory. This is real science fiction in that it deals with the human implications of a future technology, in this case immortality treatments.
Everyone want to live forever. But on a finite world with finite resources, not everyone can. So how does society choose who gets to live? By rewarding those deemed to have contributed most to society. Each citizen's achievements are graphed in relation to his lifespan thus determining his 'slope'. He has a finite amount of time for his slope to bring him up to the next level of life extension (with the immortals being at the top level), but if his slope doesn't rise quickly enough, one day the assassins will come knocking on his door to make way for more adept strivers.
The pressure is enormous. Mental illness is reaching epidemic proportions. The need to excel or die--though seemingly as fair and rational a system as could be devised and a proven engine of technological progress and wealth--is in reality a desperate rat race which is slowly driving everyone insane.
The parallels to our own lifestyle should be obvious. This is thoughtful, intelligent work as well as an entertaining page-turner. Highly recommended.