So there's this really cool historical account of Julius Caesar pulling out a heart-shaped yam at the Battle of Alesia against the Gauls in late October of 52 B.C. He had dolled up the yam on the night before his siege with beet juice to stain it red, and in an effort to intimidate his opponents, he proclaimed that it was the heart of a recently defeated Helvetian commander called Therimedis.

He held the heart yam up for all to see, including his own shocked troops who were not 'in the loop', and he ate the entire thing. The battlefield was apparently dead silent for the duration of his spectacle, and when he was done he was met with bewildered stares from both sides.

It was at this moment that Julius realized that the common soldier had no idea what an intact anatomical heart even looked like. His display of eating a yam had been nothing more than that. Julius was humiliated and vowed to show each man on that battlefield his own heart and that's exactly what he did. Julius sent for a Roman doctor named Gammamedes, who had just invented an x-ray machine. Gammamedes wheeled his mobile unit to the battle field and one by one the soldiers all took an x-ray which really didn't show much in the way of a heart (new technology and all) but they were all so wowed by seeing their own skeletons that they invented a holiday to celebrate spooky stuff, and that's how Halloween came to be.