Viral Marketing and the human condition

I found a quote in the writing of david hume (1748) which in discuss the the essence of what it is in human nature that makes viral marketing so apealing to us. He is talking about religious miracles but its equally relivant to marketing, consiracy theory general gossip.

The pleasure of telling a piece of news so interesting, of propagating it, and of being the first reporters of it, spreads the intelligence. And this is so well known, that no man of sense gives attention to these reports, till he find them confirmed by some greater evidence. Do not the same passions, and others still stronger, incline the generality of mankind to believe and report, with the greatest vehemence and assurance, all religious miracles?

http://www.soci.niu.edu/~phildept/Dye/HumeOfMiracles.html