Spit is gross but saliva is not?

But why? this was an interesting lesson in class, i thought, because we know they are exactly the same, except for the fact that ones in the mouth and ones out of the mouth. But we think that spit is gross because society tells us that it is. I have always been told as a kid to not spit but i never understood why and now i know: because society has classed spit as "gross" and saliva as a natural liquid in your mouth that should stay there. If our society formed a view about spit, like the Greeks, then maybe we would all think differently about it. The Greeks believe that spitting on the bride and groom at a wedding is good luck. This is due to their culture and how they think of the things around them differently then we do. Society has formed our thoughts about many different things that effect our lives and it will be like that forever.