Optimistic and pessimistic views on immortality

Religions are most often associated with a representation of the after-life where immortality, which is clearly unattainable in the nether-world, is ultimately achieved.
Other widely held belief systems don’t share that view, in particular Taoism, the “atheistic religion” or “philosophy” of the Chinese people over the ages. Indeed, some disparagingly called “superstitious” versions of Taoism put the stress on attaining immortality in our everyday world, recounting numerous tales of princes going to great length to secure lifesavers of various kinds. In the West, alchemy shared that same concern, being not only focused on the transmutation of antimony into gold but also on the achievement of immortality, either under the highly idealized form of a perfect identification with the person of Jesus-Christ or under the more prosaic form of the incorruptibility of the material body. Cagliostro and the count of Saint-Germain, among others, allegedly realized this aim. The British anthropological school of hyper-diffusionism, widely popular in the 1910s and 1920s (Sir Grafton Elliot Smith, William J. Perry et al.) held that culture had spread at the surface of the Earth as a consequence of the more advanced civilizations’ quest for lifesavers, the ancient Egyptians most prominently.
World representations entailing that immortality is only achievable in an after-life clearly constitute the pessimistic version of the more upbeat assumption that immortality is attainable in the material world that we’re familiar with. Now that medicine and biology are on the eve of making immortality a reality, the final push will no doubt come from these cultures which consistently envisaged immortality as an achievable pursuit: they are unencumbered by the pessimistic view that the only desirable form of immortality is the one requiring us to first die.