When President Donald Trump took the oath of office, he didn't have his hand on the Bible. Does this matter and why do politicians do it at all?

President Donald Trump, when taking his most recent oath of office, did not appear to place his left hand on either of the Bibles brought to the swearing-in ceremony in the Capitol Rotunda on Monday.

Donald Trump was sworn in as the 47th president of the United States on Monday, marking an unprecedented political comeback ...