Viktor Frankl
Author: Viktor Frankl
Publisher: Pocket Books (1997)

To draw an analogy: a man's suffering is similar to the behavior of gas.  If a certain quantity of gas is pumped into an empty chamber, it will fill the chamber completely and evenly, no matter how big the chamber.  Thus suffering completely fills the human soul and conscious mind, no matter whether the suffering is great or little.  Therefore the 'size' of human suffering is absolutely relative.