Here's why:
"He also deprived the serpent of speech, out of indignation at his malicious disposition towards Adam. Besides this, he inserted poison under his tongue, and made him an enemy to men; and suggested to them, that they should direct their strokes against his head, that being the place wherein lay his mischievous designs towards men, and it being easiest to take vengeance on him, that way. And when he had deprived him of the use of his feet, he made him to go rolling all along, and dragging himself upon the ground. And when God had appointed these penalties for them, he removed Adam and Eve out of the garden into another place." -Josephus
"For the World Is Hollow, and I Have Touched the Sky" -Star Trek. Or maybe Terrence & Phillip.
