Metaphor for the Spread of Disease

To choose a rough example, think of a thorn which has stuck in a finger and produces an inflammation and suppuration. Should the thorn be discharged with the pus, then the finger of another individual may be pricked with it, and the disease may be produced a second time. In this case it would not be the disease, not even its product, that would be transmitted by the thorn, but rather the stimulus which engendered it. Now supposing that the thorn is capable of multiplying in the sick body, or ...

 Humans Have to Keep the World Going

Pelorat said, "You know what that reminds me of? -Pardon me, Bliss, for interrupting, but it so fits that I can't resist telling you right now before I forget. There's an old creation myth I once came across; a myth in which life was formed on a planet and consisted of only a limited assortment of species, just those useful to or pleasant for humanity. The first human beings then did something silly-never mind what, old fellow, because those old myths are usually symbolic and only confusing i...