The Hand in Symbolism
Image: 30,000-year-old handprint found in Chauvet Cave in France

Our human hands are the tools with which we create our world, born out of our imagination.  They are an outer reflection of our inner selves, and are a logical basis for spiritual symbolism.  Thus, it makes sense that our hands are one of our oldest spiritual symbols, seen on cave paintings more than 300 centuries ago.