You probably have never paid attention to the way hands are depicted in religious art. But in many cases, the hands are in one of several specific different positions in stained glass, sculptures, icons, etc. Those positions follow a practice called chironomia.
Chironomia is the the art of using hand gestures to good effect in traditional rhetoric or oratory. Such gestures were used in antiquity and were used also by Christians using them to reflect specific feelings or emotions.
A good written description of hand positions in iconography is here. A YouTube video explaining hand gestures used in Christian iconography through photos of stained glass and statues in cathedrals and churches of southwest France is available here.
Some even speculate that these gestures were used by early Christians in order to communicate matters of faith during a time in which Christians could not openly express their faith.
The video also explores some gestures that might have evolved into some of the ones we see in icons and other art. While some could be circumstantial, they show how chironomia served a part in religious communication of devotion for thousands of years and clearly shows how early Christians adopted, and adapted, older Jewish or Roman hand gestures.
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