“Perhaps a more practical origin of the handshake comes from medieval Europe, where kings and knights would extend their hands to each other, and [grasp the] others hand as a demonstration that each did not possess concealed weapons and intended no harm to the other. This is a more practical origin of the handshake, because it more closely resembles our current use of the handshake as a way to introduce ourselves to a person and open ourselves up to them for the purpose of interacting. Interestingly enough, the ancient Greeks used it similarly. It was a welcoming sign of friendliness, hospitality, and trust.”

By Kevin Andrew - http://soc302.tripod.com/soc_302rocks/id8.html

Kevin Andrew on Tripod.com

"Over the many centuries of human existence, many social customs have emerged out of both necessity and leisure. The handshake is one custom that encompasses both of those origins. The handshake may appear little more than a formality to some, but to others it is a complete view into the personality of the person on the other end of the handshake. The handshake has also created nations and bought homesteads. However, in all cases it still requires two people to be executed correctly, thus causing an interaction to take place."

http://www.modernluxury.com/miami/events/symphony-lights