Handwashing: Mens Sana in Corpore Sano.....

But hand-washing was more than pragmatic:
it was also a sign of honor and civility, something you offered your guests, via a basin and towel, as soon as they arrived. Since the Greeks believed that any respectful relationship, with gods as well as humans, demanded cleanliness, washing was a necessary prelude to prayer, and sanctuaries usually had fonts of water at their entrances.

Even with antibiotics, washing off microbes remains an excellent idea. This ancient mark of courtesy is now celebrated in public health campaigns, and the Centers for Disease Control and Prevention has anointed it as “the single most important means of preventing the spread of infection.” So, learn from science as well as the wisdom of our ancestors, and wash your hands.
For the Romans and Greeks, well-washed hands were a natural accompaniment to fairly clean bodies. The medieval and Renaissance focus on clean hands is more surprising, because those ages had little interest in washing beyond the wrist. It’s true that the Crusaders imported the idea of the Turkish bath into Europe, but even if your town had a bathhouse, it merited a visit only once every week or two.
http://www.nytimes.com/2007/11/27/opinion/27ashenburg.html

Note: I have birds,and I love watching my finches,as everytime I change their water,immediately they jump into the cups and have a bath.... maybe the bird bath has origins there....(but I admit, not all birds do it )