Belief in spirit intrusion continues in some cultures today, although it was much more widespread in the ancient world. In many of these early cultures, the threshold of the home was thought to be rife with unattached spirits. A bride was considered particularly vulnerable to spirit intrusion, especially through the soles of her feet. By carrying her into their home, the groom was covering all his bases by ensuring his new wife didn't bring along any unwanted spiritual guests into the house [source: The Knot].