Man into Superman By R.C.W Ettinger

Man into Superman: The Startling Potential of Human Evolution—And How to Be Part of It is a 1972 transhumanist book written by Robert C.W. Ettinger, who is widely regarded as the "father of cryonics". 

The book serves as a philosophical and scientific sequel to his groundbreaking 1962 work, The Prospect of Immortality. While his first book focused primarily on the technical feasibility of freezing human bodies for future revival, Man into Superman explores the broader implications of what happens after humanity conquers death.