1. The idea of an embodiment of human decency, intellect, and life-force. A certain intangible that makes people "human".
2. Something most people who post on this site would apparently sell for a large fries and a Big-Gulp drink at McDonald's.
1. Even though the existence of a soul can't be proven, many people feel "connected to" others, or that humans are superior to animals in an undefinable way.
2. Milhouse gave Bart $5 for his soul on the Simpsons -- at the time this was supposed to be farcical, but like most of satire, this incedent has become a direct parallel of reality.