Excellent piece. An interesting topic for sure. The Taoists were particularly interested in immortality. Broadly speaking, there two schools of thought, neidan and waidan. The former was interested in the internal alchemy of immortality while the former was interested in its outward expression. In other words, neidan sought immortality of the spirit/mind/soul by achieving understanding of and union with the Tao. In contrast, waidan was interested in actual physical immortality. Waidan practitioners developed all sort of concoctions to achieve this goal, but often they ended up with opposite results.